STORAGE, SHIPPING, AND DISPLAY UNIT Priority Claim [0001] This patent application claims priority to and the benefit of U.S. Non-Provisional Patent Application No.17/087,179, which was filed on November 2, 2020, which claims priority to and the benefit of U.S. Provisional Patent Application No.62/932,286, which was filed on November 7, 2019, and U.S. Provisional Patent Application No.62/978,968, which was filed on February 20, 2020, the entire contents of each of which are incorporated herein by reference. Field [0002] The present disclosure relates to storage, shipping, and display units. Background [0003] In the retail industry, vendors supply products to retailers that in turn sell the products to consumers. A vendor typically packages the products (such as in a box filled with dunnage) before shipping them (such as via truck) to a retailer. After receiving the products, the retailer transfers them to a display rack and discards the packaging. These display racks are typically formed from heavy, non-recyclable material. While the display racks are reusable, they occupy a significant amount of valuable storage space when not being used and require time and labor to set up and take down, which increases costs. In some cases, the vendors ship the display racks to the retailers, in some instances with the display racks assembled and the products packaged on the display racks. Given the size and weight of these display racks, this increases freight costs and limits how far the vendors can ship the products. The vendors typically require the retailers to ship the display racks back to the vendors, which increases costs for the retailers and increases the likelihood that the display racks will be damaged or that a component will be lost in transit. Summary [0004] Various embodiments of the present disclosure provide a storage, shipping, and display unit that can be loaded with product, shipped after loading, and used as a display unit after shipment. [0005] One embodiment of the storage, shipping, and display unit of the present disclosure includes a frame, a first shelf, and a second shelf. The frame includes spaced-apart first and second shelf supports, spaced-apart first and second stretchers extending between and supported by the first and second shelf supports, and spaced-apart third and fourth shelf supports supported by the first and second stretchers. The first shelf is supported by and extends between the first and second shelf supports. The second shelf is supported by and extends between the third and fourth shelf supports. Brief Description of the Figures [0006] Figures 1A and 1B are perspective views of one example embodiment of an example support of the present disclosure. [0007] Figure 2 is a perspective view of one example embodiment of an example stretcher and an example vertical stabilizer of the present disclosure. [0008] Figure 3 is a perspective view of one example embodiment of the storage, shipping, and display unit of the present disclosure. [0009] Figure 3A is a cross-sectional top plan view of a bottom corner of the storage, shipping, and display unit of Figure 3 taken along line 3A–3A of Figure 3. [0010] Figures 4 and 5 are assembled and exploded perspective views, respectively, of the frame of the storage, shipping, and display unit of Figure 3. [0011] Figures 6 and 7 are assembled and exploded perspective views, respectively, of the frame of another embodiment of the storage, shipping, and display unit of the present disclosure. [0012] Figures 8 and 9 are assembled and exploded perspective views, respectively, of the frame of another embodiment of the storage, shipping, and display unit of the present disclosure. Detailed Description [0013] While the systems, devices, and methods described herein may be embodied in various forms, the drawings show and the specification describes certain exemplary and non-limiting embodiments. Not all of the components shown in the drawings and described in the specification may be required, and certain implementations may include additional, different, or fewer components. Variations in the arrangement and type of the components; the shapes, sizes, and materials of the components; and the manners of connections of the components may be made without departing from the spirit or scope of the claims. Unless otherwise indicated, any directions referred to in the specification reflect the orientations of the components shown in the corresponding drawings and do not limit the scope of the present disclosure. Further, terms that refer to mounting methods, such as mounted, connected, etc., are not intended to be limited to direct mounting methods but should be interpreted broadly to include indirect and operably mounted, connected, and like mounting methods. This specification is intended to be taken as a whole and interpreted in accordance with the principles of the present disclosure and as understood by one of ordinary skill in the art. [0014] Various embodiments of the present disclosure provide a storage, shipping, and display unit formed from multiple supports, multiple stretchers, multiple vertical stabilizers, and multiple shelves. [0015] Figures 1A and 1B show an example support SU. As described below, the support SU is an example of the base support, the top support, and the shelf supports of the storage, shipping, and display unit. These different types of supports may have different sizes, but include the same components. The support SU includes first, second, third, and fourth legs 10, 20, 30, and 40, respectively, connected to one another and oriented to form a rectangular shape. Each leg includes two transversely oriented walls that (at least in this example embodiment) form an L-shape. [0016] More specifically, the first leg 10 includes a first wall 12 having an outer surface 12o and an opposing inner surface 12i and a second wall 14 having an outer surface 14o and an opposing inner surface 14i. The first wall 12 is connected to (and in this embodiment integrally formed with) the second wall 14 and oriented so the first wall 12 is transverse to (and in this embodiment perpendicular to) the second wall 14. The second leg 20 includes a first wall 22 having an outer surface 22o and an opposing inner surface 22i and a second wall 24 having an outer surface 24o and an opposing inner surface 24i. The first wall 22 is connected to (and in this embodiment integrally formed with) the second wall 24 and oriented so the first wall 22 is transverse to (and in this embodiment perpendicular to) the second wall 24. The third leg 30 includes a first wall 32 having an outer surface 32o and an opposing inner surface 32i and a second wall 34 having an outer surface 34o and an opposing inner surface 34i. The first wall 32 is connected to (and in this embodiment integrally formed with) the second wall 34 and oriented so the first wall 32 is transverse to (and in this embodiment perpendicular to) the second wall 34. The fourth leg 40 includes a first wall 42 having an outer surface 42o and an opposing inner surface 42i and a second wall 44 having an outer surface 44o and an opposing inner surface 44i. The first wall 42 is connected to (and in this embodiment integrally formed with) the second wall 44 and oriented so the first wall 42 is transverse to (and in this embodiment perpendicular to) the second wall 44. [0017] As best shown in Figure 1A, the legs 10, 20, 30, and 40 have respective lengths L10, L ₂₀ , L ₃₀ , and L ₄₀ . These lengths generally correspond to the length of the first walls 12, 22, 32, and 42 of the respective legs. The widths and thicknesses (neither of which are labeled) of the walls may be selected as desired for the intended application. [0018] The first leg 10 is connected to the second leg 20, and the first leg 10 and the second leg 20 are oriented transversely to (and in this embodiment perpendicular to) one another. In this example embodiment, the first wall 12 of the first leg 10 and the first wall 22 of the second leg 20 are integrally formed with one another and bent to achieve this orientation. The second leg 20 is connected to the third leg 30, and the second leg 20 and the third leg 30 are oriented transversely to (and in this embodiment perpendicular to) one another. In this example embodiment, the second wall 24 of the second leg 20 and the second wall 34 of the third leg 30 are connected via a connector 50b to achieve this orientation. The connector 50b may be any suitable connector, such as a mechanical fastener (staple, rivet, etc.); adhesive; or tape. The third leg 30 is connected to the fourth leg 40, and the third leg 30 and the fourth leg 40 are oriented transversely to (and in this embodiment perpendicular to) one another. In this example embodiment, the first wall 32 of the third leg 30 and the first wall 42 of the fourth leg 40 are integrally formed with one another and bent to achieve this orientation. The fourth leg 40 is connected to the first leg 10, and the fourth leg 40 and the first leg 10 are oriented transversely to (and in this embodiment perpendicular to) one another. In this example embodiment, the second wall 44 of the fourth leg 40 and the second wall 14 of the first leg 10 are connected via a connector 50a to achieve this orientation. The connector 50a may be any suitable connector referenced above. [0019] As best shown in Figure 1A, opposing pairs of legs of the support SU are approximately the same length so the support SU forms a rectangular shape. That is, in this example embodiment, the lengths L ₁₀ and L ₃₀ of the opposing legs 10 and 30 are approximately the same length, and the lengths L ₂₀ and L ₄₀ of the opposing legs 20 and 40 are approximately the same length. Varying the lengths L ₁₀ , L ₂₀ , L ₃₀ , and L ₄₀ of the legs 10, 20, 30, and 40 varies the size of the support SU. [0020] In this example embodiment, the legs 10, 20, 30, and 40 are formed from recycled and recyclable material: multiple plies of paperboard laminated together with a suitable adhesive (such water or non-water-based polyvinyl acetate adhesive, a sodium silicate adhesive, or a potato starch adhesive). In other embodiments, the legs may be formed from any other suitable material, such as non- recycled and/or recyclable material, biodegradable material, plant-based material, and the like. [0021] In other embodiments, the first walls of the second and third legs are integrally formed with one another and bent to achieve the described orientation. In some embodiments, the first walls of the first and fourth legs are integrally formed with one another and bent to achieve the described orientation. [0022] Figure 2 shows an example stretcher ST/vertical stabilizer V. In this example embodiment, the stretchers ST and the vertical stabilizers V are generally the same shape (though may have different sizes) and are shown and described with reference to the single component shown in Figure 2 for brevity (though in other embodiments these components may differ). The stretcher ST/vertical stabilizer V includes first and second walls 60 and 70, respectively, connected to and transversely oriented relative to one another to form an L-shape. More specifically, the first wall 60 has an outer surface 62o and an opposing inner surface 62i, and the second wall 70 has an outer surface 72o and an opposing inner surface 72i. The first wall 60 is connected to (and in this embodiment integrally formed with) the second wall 70 and oriented so the first wall 60 is transverse to (and in this embodiment perpendicular to) the second wall 70. [0023] The stretcher ST/vertical stabilizer V has a length LST/LV, which generally corresponds to the lengths of the first and second walls 60 and 70. The widths and thicknesses (neither of which are labeled) of the walls may be selected as needed for the desired application of the stretcher ST/vertical stabilizer V. [0024] In this example embodiment, the stretcher ST/vertical stabilizer V is formed from recycled and recyclable material: multiple plies of paperboard laminated together with a suitable adhesive (such a water or non-water-based polyvinyl acetate adhesive, a sodium silicate adhesive, or a potato starch adhesive). In other embodiments, the stretcher/vertical stabilizer may be formed from any other suitable material, such as such as non- recycled and/or recyclable material, biodegradable material, plant-based material, and the like. [0025] Figures 3, 4, and 5 show one example embodiment of the storage, shipping, and display unit E1. The storage, shipping, and display unit E1 includes: a base support BS; shelf supports SU ₁₀₀ , SU ₂₀₀ , SU ₃₀₀ , SU ₄₀₀ , SU ₅₀₀ , SU ₆₀₀ , SU ₇₀₀ , and SU ₈₀₀ ; a top support TS; stretchers ST ₁₀₀ , ST ₂₀₀ , ST ₃₀₀ , ST ₄₀₀ , ST ₅₀₀ , ST ₆₀₀ , ST ₇₀₀ , and ST ₈₀₀ ; shelves SH ₁ , SH ₂ , SH ₃ , and SH ₄ ; and vertical stabilizers V ₁₀₀ , V ₂₀₀ , V ₃₀₀ , and V ₄₀₀ . The storage, shipping, and display unit E1 has a height H _E1 , a width W _E1 , and a depth D _E1 . For clarity, the supports are showed in simplified form in the drawings, though they are generally the same as the support SU shown in Figures 1A and 1B. [0026] In this example embodiment: the base and top supports BS and TS are the same size and shape; the shelf supports SU ₁₀₀ , SU ₂₀₀ , SU ₅₀₀ , and SU ₆₀₀ are the same size and shape; the shelf supports SU ₃₀₀ , SU ₄₀₀ , SU ₇₀₀ , and SU ₈₀₀ are the same size and shape; the stretchers ST ₁₀₀ , ST ₂₀₀ , ST ₅₀₀ , and ST ₆₀₀ are the same size and shape; the stretchers ST ₃₀₀ , ST ₄₀₀ , ST ₇₀₀ , and ST ₈₀₀ are the same size and shape; the vertical stabilizers V ₁₀₀ –V ₄₀₀ are the same size and shape; and the shelves SH ₁ –SH ₄ are the same size and shape. [0027] Generally, and as best shown in Figures 4 and 5, the shelf supports SU ₁₀₀ –SU ₈₀₀ and the stretchers ST ₁₀₀ –ST ₈₀₀ are arranged to form a frame F1 that supports the shelves SH1– SH4. More specifically, the frame F1 is formed of multiple frame layers L1, L2, L3, and L4, each of which includes a spaced-apart pair of the shelf supports SU ₁₀₀ –SU ₈₀₀ that together support one of the shelves SH ₁ –SH ₄ . A pair of the stretchers ST ₁₀₀ –ST ₈₀₀ separates consecutive frame layers. In this example embodiment, the pair of shelf supports in a given frame layer are oriented transversely (and more particularly, perpendicularly) to the pair(s) of shelf supports in the frame layers above and below that given frame layer. Put differently, in this example embodiment the pairs of shelf supports alternate in orientation from frame layer to frame layer. As shown in Figure 3, the vertical stabilizers V ₁₀₀ –V ₄₀₀ extend along the four corners of the frame F1. The base and top supports BS and TS tie together the bottom and top (respectively) of the frame F1 and the vertical stabilizers V ₁₀₀ –V ₄₀₀ . [0028] The orientations of the components of the storage, shipping, and display unit E1 are described below with respect to a coordinate system C shown in Figure 3. The coordinate system includes X-, Y-, and Z-directions that are transverse to (and here, perpendicular to) one another. [0029] As noted above, the support SU shown in Figures 1A and 1B is an example representation of the base support BS, the shelf supports SU ₁₀₀ –SU ₈₀₀ , and the top support TS. The components of the supports BS, SU ₁₀₀ –SU ₈₀₀ , and TS thus have the same components as the example support SU. For clarity and brevity, the components of the supports BS, SU ₁₀₀ –SU ₈₀₀ , and TS are identified below with the same numbering convention used in Figures 1A and 1B with the addition of a prefix that corresponds to the particular support: the prefix is “BS” for the base support BS, the prefixes “1” through “8” for the shelf supports SU ₁₀₀ –SU ₈₀₀ , and the prefix “TS” for the top support TS. For instance, the first leg of the shelf support SU ₁₀₀ is identified using element number 110, and the first wall of the fourth leg of the top support TS is identified using element number TS42. The individual elements of these components are not labeled in the drawings for clarity. [0030] The components of the stretchers ST ₁₀₀ –ST ₈₀₀ have the same components as the example stretcher ST/vertical stabilizer V shown in Figure 2. For clarity and brevity, the components of the stretchers ST ₁₀₀ –ST ₈₀₀ are identified below with the same numbering convention used in Figure 2 with the addition of a prefix number that corresponds to the particular stretcher: the prefixes “1” through “8” for the stretchers ST ₁₀₀ –ST ₈₀₀ . For instance, the first wall of the stretcher ST ₃₀₀ is identified using element number 360. The individual elements of these components are not labeled in the drawings for clarity. [0031] The components of the vertical stabilizers V ₁₀₀ –V ₄₀₀ have the same components as the example stretcher ST/vertical stabilizer V shown in Figure 2. For clarity and brevity, the components of the vertical stabilizers V ₁₀₀ –V ₄₀₀ are identified below with the same numbering convention used in Figure 2 with the addition of a prefix number that corresponds to the particular vertical stabilizer: the prefixes “1” through “4” for the vertical stabilizers V100–V400. For instance, the second wall of the vertical stabilizer V ₄₀₀ is identified using element number 470. The individual elements of these components are not labeled in the drawings for clarity. [0032] Starting from the bottom of the storage, shipping, and display unit E1, the base support BS is positioned on (and in some embodiments attached to) and supported by a pallet (not shown) so the outer surfaces BS14o, BS24o, BS34o, and BS44o of the second walls BS14, BS24, BS34, and BS44 of the legs BS10, BS20, BS30, and BS40 of the base support BS engage the pallet and so the inner surfaces BS14i, BS24i, BS34i, and BS44i of the second walls BS14, BS24, BS34, and BS44 of the legs BS10, BS20, BS30, and BS40 of the base support BS face away from the pallet. The base support BS is oriented generally parallel to the X–Z plane. [0033] The shelf support SU ₁₀₀ nests into and is supported by the base support BS. More specifically, the shelf support SU ₁₀₀ is positioned and oriented so: (1) the outer surface 112o of the first wall 112 of the first leg 110 of the shelf support SU ₁₀₀ engages the inner surface BS14i of the second wall BS14 of the first leg BS10 of the base support BS; (2) the outer surface 114a of the second wall 114 of the first leg 110 of the shelf support SU ₁₀₀ engages the inner surface BS12i of the first wall BS12 of the first leg BS10 of the base support BS; (3) the fourth leg 140 of the shelf support SU ₁₀₀ extends upward in the Y-direction from the junction of the first and second legs BS10 and BS20 of the base support BS _; and (4) the second leg 120 of the shelf support SU ₁₀₀ extends upward in the Y-direction from the junction of the first and fourth legs BS10 and BS40 of the base support BS. In this orientation, the first and third legs 110 and 130 of the shelf support SU ₁₀₀ extend generally horizontally in the X-direction, the second and fourth legs 120 and 140 of the shelf support SU ₁₀₀ extend generally vertically in the Y-direction, and the shelf support SU ₁₀₀ is oriented generally parallel to the X–Y plane. In certain embodiments, the shelf support SU ₁₀₀ is attached to the base support BS in any suitable manner, such as via mechanical fasteners (such as staples, pins, or brads); adhesives; or tape. [0034] The shelf support SU ₂₀₀ nests into and is supported by the base support BS. More specifically, the shelf support SU ₂₀₀ is positioned and oriented so: (1) the outer surface 212o of the first wall 212 of the first leg 210 of the shelf support SU ₂₀₀ engages the inner surface BS34i of the second wall BS34 of the third leg BS30 of the base support BS; (2) the outer surface 214a of the second wall 214 of the first leg 210 of the shelf support SU ₂₀₀ engages the inner surface BS32i of the first wall BS32 of the third leg BS30 of the base support BS; (3) the fourth leg 240 of the shelf support SU ₂₀₀ extends upward in the Y-direction from the junction of the third and fourth legs BS30 and BS40 of the base support BS; and (4) the second leg 220 of the shelf support SU ₂₀₀ extends upward in the Y-direction from the junction of the second and third legs BS20 and BS30 of the base support BS. In this orientation, therefore, the first and third legs 210 and 230 of the shelf support SU ₂₀₀ extend generally horizontally in the X-direction, the second and fourth legs 220 and 240 of the shelf support SU ₂₀₀ extend generally vertically in the Y-direction, and the shelf support SU ₂₀₀ is oriented generally parallel to the X–Y plane and spaced-apart from the shelf support SU ₂₀₀ in the Z- direction. In certain embodiments, the shelf support SU ₂₀₀ is attached to the base support BS in any suitable manner, such as any of those referenced above. [0035] The stretcher ST ₁₀₀ is supported by and extends between and connects the shelf supports SU ₁₀₀ and SU ₂₀₀ . More specifically, the stretcher ST ₁₀₀ is positioned and oriented so: (1) the inner surface 162i of the first wall 160 of the stretcher ST ₁₀₀ engages the outer surfaces 132o and 232o of the first walls 132 and 232 of the third legs 130 and 230 of the shelf supports SU ₁₀₀ and SU200; and (2) the inner surface 172i of the second wall 170 of the stretcher ST1 ₀₀ engages the outer surface 142o of the first wall 142 of the fourth leg 140 of the shelf support SU ₁₀₀ and engages the outer surface 222o of the first wall 222 of the second leg 220 of the shelf support SU ₂₀₀ . In this orientation, the stretcher ST ₁₀₀ extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₁₀₀ is attached to the shelf supports SU ₁₀₀ and SU ₂₀₀ in any suitable manner, such as any of those referenced above. [0036] The stretcher ST ₂₀₀ is supported by and extends between and connects the shelf supports SU ₁₀₀ and SU ₂₀₀ . More specifically, the stretcher ST ₂₀₀ is positioned and oriented so: (1) the inner surface 262i of the first wall 260 of the stretcher ST ₂₀₀ engages the outer surfaces 132o and 232o of the first walls 132 and 232 of the third legs 130 and 230 of the shelf supports SU ₁₀₀ and SU ₂₀₀ ; and (2) the inner surface 272i of the second wall 270 of the stretcher ST ₂₀₀ engages the outer surface 122o of the first wall 122 of the second leg 120 of the shelf support SU ₁₀₀ and engages the outer surface 242o of the first wall 242 of the fourth leg 240 of the shelf support SU ₂₀₀ . In this orientation, the stretcher ST ₂₀₀ extends generally horizontally in the Z-direction and is spaced-apart from the stretcher ST ₁₀₀ in the X-direction. In certain embodiments, the stretcher ST ₁₀₀ is attached to the shelf supports SU ₁₀₀ and SU ₂₀₀ in any suitable manner, such as any of those referenced above. [0037] The shelf support SU300 is supported by the stretcher ST ₁₀₀ . More specifically, the shelf support SU ₃₀₀ is positioned and oriented so: (1) the outer surface 312o of the first wall 312 of the first leg 310 of the shelf support SU ₃₀₀ engages the outer surface 162o of the first wall 162 of the stretcher ST ₁₀₀ ; (2) the second leg 320 of the shelf support SU ₃₀₀ extends generally vertically in the Y- direction and is positioned above the fourth leg 140 of the shelf support SU ₁₀₀ ; and (3) the fourth leg 340 of the shelf support SU ₃₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 220 of the shelf support SU ₂₀₀ . In this orientation, the first and third legs 310 and 330 of the shelf support SU300 extend generally horizontally in the Z-direction, and the shelf support SU ₃₀₀ is oriented generally parallel to the Y–Z plane. In certain embodiments, the shelf support SU ₃₀₀ is attached to the stretcher ST ₁₀₀ in any suitable manner, such as any of those referenced above. [0038] The shelf support SU ₄₀₀ is supported by the stretcher ST ₂₀₀ . More specifically, the shelf support SU400 is positioned and oriented so: (1) the outer surface 412o of the first wall 412 of the first leg 410 of the shelf support SU ₄₀₀ engages the outer surface 262o of the first wall 262 of the stretcher ST ₂₀₀ ; (2) the second leg 420 of the shelf support SU ₄₀₀ extends generally vertically in the Y- direction and is positioned above the fourth leg 240 of the shelf support SU ₂₀₀ ; and (3) the fourth leg 440 of the shelf support SU400 extends generally vertically in the Y-direction and is positioned above the second leg 120 of the shelf support SU ₁₀₀ . In this orientation, the first and third legs 410 and 430 of the shelf support SU ₄₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₄₀₀ is oriented generally parallel to the Y–Z plane and spaced-apart from the shelf support SU ₃₀₀ in the X-direction. In certain embodiments, the shelf support SU ₄₀₀ is attached to the stretcher ST200 in any suitable manner, such as any of those referenced above. [0039] The stretcher ST ₃₀₀ is supported by and extends between and connects the shelf supports SU ₃₀₀ and SU ₄₀₀ . More specifically, the stretcher ST ₃₀₀ is positioned and oriented so: (1) the inner surface 362i of the first wall 360 of the stretcher ST300 engages the outer surfaces 332o and 432o of the first walls 332 and 432 of the third legs 330 and 430 of the shelf supports SU ₃₀₀ and SU ₄₀₀ ; and (2) the inner surface 372i of the second wall 370 of the stretcher ST ₃₀₀ engages the outer surface 322o of the first wall 322 of the second leg 320 of the shelf support SU ₃₀₀ and the outer surface 442o of the first wall 442 of the fourth leg 440 of the shelf support SU ₄₀₀ . In this orientation, the stretcher ST ₃₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₃₀₀ is attached to the shelf supports SU ₃₀₀ and SU ₄₀₀ in any suitable manner, such as any of those referenced above. [0040] The stretcher ST400 is supported by and extends between and connects the shelf supports SU ₃₀₀ and SU ₄₀₀ . More specifically, the stretcher ST ₄₀₀ is positioned and oriented so: (1) the inner surface 462i of the first wall 460 of the stretcher ST ₄₀₀ engages the outer surfaces 332o and 432o of the first walls 332 and 432 of the third legs 330 and 430 of the shelf supports SU ₃₀₀ and SU ₄₀₀ ; and (2) the inner surface 472i of the second wall 470 of the stretcher ST ₄₀₀ engages the outer surface 342o of the first wall 342 of the fourth leg 340 of the shelf support SU ₃₀₀ and the outer surface 422o of the first wall 422 of the second leg 420 of the shelf support SU ₄₀₀ . In this orientation, the stretcher ST ₄₀₀ extends generally horizontally in the X-direction and is spaced apart from the stretcher ST ₃₀₀ in the Z-direction. In certain embodiments, the stretcher ST ₄₀₀ is attached to the shelf supports SU ₃₀₀ and SU ₄₀₀ in any suitable manner, such as any of those referenced above. [0041] The shelf support SU ₅₀₀ is supported by the stretcher ST ₃₀₀ . More specifically, the shelf support SU ₅₀₀ is positioned and oriented so: (1) the outer surface 512o of the first wall 512 of the first leg 510 of the shelf support SU500 engages the outer surface 362o of the first wall 362 of the stretcher ST ₃₀₀ ; (2) the second leg 520 of the shelf support SU500 extends generally vertically in the Y- direction and is positioned above the fourth leg 440 of the shelf support SU ₄₀₀ ; and (3) the fourth leg 540 of the shelf support SU ₅₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 320 of the shelf support SU ₃₀₀ . In this orientation, the first and third legs 510 and 530 of the shelf support SU ₅₀₀ extend generally horizontally in the X-direction, and the shelf support SU ₅₀₀ is oriented generally parallel to the X–Y plane. In certain embodiments, the shelf support SU ₅₀₀ is attached to the stretcher ST ₃₀₀ in any suitable manner, such as any of those referenced above. [0042] The shelf support SU ₆₀₀ is supported by the stretcher ST ₄₀₀ . More specifically, the shelf support SU ₆₀₀ is positioned and oriented so: (1) the outer surface 612o of the first wall 612 of the first leg 610 of the shelf support SU ₆₀₀ engages the outer surface 462o of the first wall 462 of the stretcher ST ₄₀₀ ; (2) the second leg 620 of the shelf support SU ₆₀₀ extends generally vertically in the Y- direction and is positioned above the fourth leg 340 of the shelf support SU ₃₀₀ ; and (3) the fourth leg 640 of the shelf support SU ₆₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 420 of the shelf support SU ₄₀₀ . In this orientation, the first and third legs 610 and 630 of the shelf support SU ₆₀₀ extend generally horizontally in the X-direction, and the shelf support SU ₆₀₀ is oriented generally parallel to the X–Y plane and spaced-apart from the shelf support SU ₅₀₀ in the Z-direction. In certain embodiments, the shelf support SU ₆₀₀ is attached to the stretcher ST ₄₀₀ in any suitable manner, such as any of those referenced above. [0043] The stretcher ST ₅₀₀ is supported by and extends between and connects the shelf supports SU ₅₀₀ and SU ₆₀₀ . More specifically, the stretcher ST ₅₀₀ is positioned and oriented so: (1) the inner surface 562i of the first wall 560 of the stretcher ST ₅₀₀ engages the outer surfaces 532o and 632o of the first walls 532 and 632 of the third legs 530 and 630 of the shelf supports SU ₅₀₀ and SU ₆₀₀ ; and (2) the inner surface 572i of the second wall 570 of the stretcher ST ₅₀₀ engages the outer surface 542o of the first wall 542 of the fourth leg 540 of the shelf support SU500 and engages the outer surface 622o of the first wall 622 of the second leg 620 of the shelf support and SU ₆₀₀ . In this orientation, the stretcher ST ₅₀₀ extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₅₀₀ is attached to the shelf supports SU ₅₀₀ and SU ₆₀₀ in any suitable manner, such as any of those referenced above. [0044] The stretcher ST ₆₀₀ is supported by and extends between and connects the shelf supports SU ₅₀₀ and SU ₆₀₀ . More specifically, the stretcher ST ₆₀₀ is positioned and oriented so: (1) the inner surface 662i of the first wall 660 of the stretcher ST ₆₀₀ engages the outer surfaces 532o and 632o of the first walls 532 and 632 of the third legs 530 and 630 of the shelf supports SU ₅₀₀ and SU ₅₀₀ ; and (2) the inner surface 672i of the second wall 670 of the stretcher ST ₆₀₀ engages the outer surface 522o of the first wall 522 of the second leg 520 of the shelf support SU ₅₀₀ and engages the outer surface 642o of the first wall 642 of the fourth leg 640 of the shelf support SU ₆₀₀ . In this orientation, the stretcher ST ₆₀₀ extends generally horizontally in the Z-direction and is spaced-apart from the stretcher ST500 in the X-direction. In certain embodiments, the stretcher ST ₆₀₀ is attached to the shelf supports SU ₅₀₀ and SU ₆₀₀ in any suitable manner, such as any of those referenced above. [0045] The shelf support SU ₇₀₀ is supported by the stretcher ST ₅₀₀ . More specifically, the shelf support SU ₇₀₀ is positioned and oriented so: (1) the outer surface 712o of the first wall 712 of the first leg 710 of the shelf support SU ₇₀₀ engages the outer surface 562o of the first wall 562 of the stretcher ST ₅₀₀ ; (2) the second leg 720 of the shelf support SU ₇₀₀ extends generally vertically in the Y- direction and is positioned above the fourth leg 540 of the shelf support SU ₅₀₀ ; and (3) the fourth leg 740 of the shelf support SU ₇₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 620 of the shelf support SU ₆₀₀ . In this orientation, the first and third legs 710 and 730 of the shelf support SU ₇₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₇₀₀ is oriented generally parallel to the Y–Z plane. In certain embodiments, the shelf support SU ₇₀₀ is attached to the stretcher ST ₅₀₀ in any suitable manner, such as any of those referenced above. [0046] The shelf support SU ₈₀₀ is supported by the stretcher ST ₆₀₀ . More specifically, the shelf support SU ₈₀₀ is positioned and oriented so: (1) the outer surface 812o of the first wall 812 of the first leg 810 of the shelf support SU ₈₀₀ engages the outer surface 662o of the first wall 662 of the stretcher ST ₆₀₀ ; (2) the second leg 820 of the shelf support SU ₈₀₀ extends generally vertically in the Y- direction and is positioned above the fourth leg 640 of the shelf support SU ₆₀₀ ; and (3) the fourth leg 840 of the shelf support SU ₈₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 520 of the shelf support SU ₅₀₀ . In this orientation, the first and third legs 810 and 830 of the shelf support SU ₈₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₈₀₀ is oriented generally parallel to the Y–Z plane and spaced-apart from the shelf support SU ₇₀₀ in the X-direction. In certain embodiments, the shelf support SU ₈₀₀ is attached to the stretcher ST ₆₀₀ in any suitable manner, such as any of those referenced above. [0047] The stretcher ST ₇₀₀ is supported by and extends between and connects the shelf supports SU ₇₀₀ and SU ₈₀₀ . More specifically, the stretcher ST ₇₀₀ is positioned and oriented so: (1) the inner surface 762i of the first wall 760 of the stretcher ST ₇₀₀ engages the outer surfaces 732o and 832o of the first walls 732 and 832 of the third legs 730 and 830 of the shelf supports SU ₇₀₀ and SU800; and (2) the inner surface 772i of the second wall 770 of the stretcher ST ₇₀₀ engages the outer surface 722o of the first wall 722 of the second leg 720 of the shelf support SU ₇₀₀ and the outer surface 842o of the first wall 842 of the fourth leg 840 of the shelf support SU ₉₀₀ . In this orientation, the stretcher ST ₇₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₇₀₀ is attached to the shelf supports SU ₇₀₀ and SU ₈₀₀ in any suitable manner, such as any of those referenced above. [0048] The stretcher ST ₈₀₀ is supported by and extends between and connects the shelf supports SU ₇₀₀ and SU ₈₀₀ . More specifically, the stretcher ST ₈₀₀ is positioned and oriented so: (1) the inner surface 862i of the first wall 860 of the stretcher ST ₈₀₀ engages the outer surfaces 732o and 832o of the first walls 732 and 832 of the third legs 730 and 830 of the shelf supports SU ₇₀₀ and SU ₈₀₀ ; and (2) the inner surface 872i of the second wall 870 of the stretcher ST ₈₀₀ engages the outer surface 742o of the first wall 742 of the fourth leg 740 of the shelf support SU ₇₀₀ and the outer surface 822o of the first wall 822 of the second leg 820 of the shelf support SU ₈₀₀ . In this orientation, the stretcher ST ₈₀₀ extends generally horizontally in the X-direction and is spaced-apart from the stretcher ST ₇₀₀ in the Z-direction. In certain embodiments, the stretcher ST ₈₀₀ is attached to the shelf supports SU ₇₀₀ and SU ₈₀₀ in any suitable manner, such as any of those referenced above. [0049] The top support TS is positioned and oriented so the inner surfaces TS14i and TS34i of the second walls TS14 and TS34 of the legs TS10 and TS30 of the top support TS respectively engage the outer surface 762o of the first wall 760 of the stretcher ST ₇₀₀ and the outer surface 862o of the first wall 860 of the stretcher ST ₈₀₀ . The top support TS is oriented generally parallel to the X–Z plane and spaced apart from the base support BS in the Y-direction. In certain embodiments, the top support TS is attached to stretchers ST700 and ST ₈₀₀ in any suitable manner, such as any of those referenced above. [0050] The vertical stabilizer V ₁₀₀ extends generally vertically in the Y-direction from the junction between the first and fourth legs BS10 and BS40 of the base support BS to the junction between the first and second legs TS10 and TS20 of the top support TS. The bottom of the vertical stabilizer V ₁₀₀ is sandwiched between the base support BS and the shelf support SU ₁₀₀ , and the top of the vertical stabilizer V ₁₀₀ is sandwiched between the top support TS and the stretcher ST ₇₀₀ . The vertical stabilizer V ₁₀₀ is generally aligned with the second leg 120 of the shelf support SU ₁₀₀ , the fourth leg 440 of the shelf support SU ₄₀ 0, the second leg 520 of the shelf support SU ₅₀₀ , and the fourth leg 840 of the shelf support SU ₈₀₀ such that the inner surfaces 162i and 172i of the first and second walls 160 and 170 of the vertical stabilizer V ₁₀₀ face (and in certain embodiments engage) the legs. In certain embodiments, the vertical stabilizer V ₁₀₀ is attached to one or more of these components in any suitable manner, such as any of those referenced above. [0051] The vertical stabilizer V ₂₀₀ extends generally vertically in the Y-direction from the junction between the first and second legs BS10 and BS20 of the base support BS to the junction between the first and fourth legs TS10 and TS40 of the top support TS. The bottom of the vertical stabilizer V ₂₀₀ is sandwiched between the base support BS and the shelf support SU ₁₀₀ (as shown in Figure 3A), and the top of the vertical stabilizer V ₂₀₀ is sandwiched between the top support TS and the stretcher ST700. The vertical stabilizer V ₂₀₀ is generally aligned with the fourth leg 140 of the shelf support SU ₁₀₀ , the second leg 320 of the shelf support SU300, the fourth leg 540 of the shelf support SU ₅₀₀ , and the second leg 720 of the shelf support SU ₇₀₀ such that the inner surfaces 262i and 272i of the first and second walls 260 and 270 of the vertical stabilizer V ₂₀₀ face (and in certain embodiments engage) the legs. In certain embodiments, the vertical stabilizer V ₂₀₀ is attached to one or more of these components in any suitable manner, such as any of those referenced above. [0052] The vertical stabilizer V ₃₀₀ extends generally vertically in the Y-direction from the junction between the second and third legs BS20 and BS30 of the base support BS to the junction between the third and fourth legs TS30 and TS40 of the top support TS. The bottom of the vertical stabilizer V ₃₀₀ is sandwiched between the base support BS and the shelf support SU ₂₀₀ , and the top of the vertical stabilizer V ₃₀₀ is sandwiched between the top support TS and the stretcher ST ₈₀₀ . The vertical stabilizer V ₃₀₀ is generally aligned with the second leg 220 of the shelf support SU ₂₀₀ , the fourth leg 340 of the shelf support SU ₃₀₀ , the second leg 620 of the shelf support SU ₆₀₀ , and the fourth leg 740 of the shelf support SU ₇₀₀ such that the inner surfaces 362i and 372i of the first and second walls 360 and 370 of the vertical stabilizer V ₃₀₀ face (and in certain embodiments engage) the legs. In certain embodiments, the vertical stabilizer V ₃₀₀ is attached to one or more of these components in any suitable manner, such as any of those referenced above. [0053] The vertical stabilizer V ₄₀₀ extends generally vertically in the Y-direction from the junction between the third and fourth legs BS30 and BS40 of the base support BS to the junction between the second and third legs TS20 and TS30 of the top support TS. The bottom of the vertical stabilizer V ₄₀₀ is sandwiched between the base support BS and the shelf support SU ₂₀₀ , and the top of the vertical stabilizer V ₄₀₀ is sandwiched between the top support TS and the stretcher ST800. The vertical stabilizer V ₄₀₀ is generally aligned with the fourth leg 240 of the shelf support SU ₂₀₀ , the second leg 420 of the shelf support SU ₄₀₀ , the fourth leg 640 of the shelf support SU ₆₀₀ , and the second leg 820 of the shelf support SU ₈₀₀ such that the inner surfaces 462i and 472i of the first and second walls 460 and 470 of the vertical stabilizer V400 face (and in certain embodiments engage) the legs. In certain embodiments, the vertical stabilizer V ₄₀₀ is attached to one or more of these components in any suitable manner, such as any of those referenced above. [0054] The shelves SH1–SH4 are rectangular cuboid in shape and are formed from any suitable material or materials. In this example embodiment, the shelves include opposing top and bottom facing layers of paper or corrugated material that sandwich core material in between (such as honeycomb material . In other embodiments, the shelves may be formed from any suitable material, such as built-up corrugated material or plastic. [0055] The shelf SH ₁ extends between and is supported by the shelf supports SU ₁₀₀ and SU ₂₀₀ . Specifically, the bottom surface of the shelf SH ₁ engages the inner surfaces 112i and 212i of the first walls 112 and 212 of the first legs 110 and 210 of the shelf supports SU ₁₀₀ and SU ₂₀₀ so the shelf SH1 is oriented generally parallel to the X–Z plane. The shelf SH1 is sized and shaped so installing the shelf SH ₁ forces the shelf supports SU ₁₀₀ and SU ₂₀₀ away from one another against the vertical stabilizers V ₁₀₀ –V ₄₀₀ , which in turn forces the vertical stabilizers V ₁₀₀ –V ₄₀₀ against the base support BS. This adds rigidity to the storage, shipping, and display unit E1 and ensures the shelf SH1 is held in place via interference fit. The walls of the first, second, and fourth legs of the shelf supports SU ₁₀₀ and SU ₂₀₀ prevent substantial back-and-forth and side-to-side movement of the shelf SH ₁ in the X- and Z-directions relative to the other components of the storage, shipping, and display unit E1. In certain embodiments, the shelf SH1 is attached to one or more of the shelf supports SU ₁₀₀ and SU ₂₀₀ in any suitable manner, such as any of those referenced above. [0056] The shelf SH ₂ extends between and is supported by the shelf supports SU ₃₀₀ and SU ₄₀₀ . Specifically, the bottom surface of the shelf SH ₂ engages the inner surfaces 312i and 412i of the first walls 312 and 412 of the first legs 310 and 410 of the shelf supports SU ₃₀₀ and SU ₄₀₀ so the shelf SH2 is oriented generally parallel to the X–Z plane. The shelf SH2 is sized and shaped so installing the shelf SH ₂ forces the shelf supports SU ₃₀₀ and SU ₄₀₀ away from one another and against the vertical stabilizers V ₁₀₀ –V ₄₀₀ . This adds rigidity to the storage, shipping, and display unit E1 and ensures the shelf SH ₂ is held in place via interference fit. The walls of the first, second, and fourth legs of the shelf supports SU ₃₀₀ and SU ₄₀₀ prevent substantial back-and-forth and side-to-side movement of the shelf SH ₂ in the X- and Z-directions relative to the other components of the storage, shipping, and display unit E1. In certain embodiments, the shelf SH ₂ is attached to one or more of the shelf supports SU ₃₀₀ and SU ₄₀₀ in any suitable manner, such as any of those referenced above. [0057] The shelf SH ₃ extends between and is supported by the shelf supports SU ₅₀₀ and SU ₆₀₀ . Specifically, the bottom surface of the shelf SH3 engages the inner surfaces 512i and 612i of the first walls 512 and 612 of the first legs 510 and 610 of the shelf supports SU ₅₀₀ and SU ₆₀₀ so the shelf SH ₃ is oriented generally parallel to the X–Z plane. The shelf SH ₃ is sized and shaped so installing the shelf SH ₃ forces the shelf supports SU ₅₀₀ and SU ₆₀₀ away from one another and against the vertical stabilizers V ₁₀₀ –V ₄₀₀ . This adds rigidity to the storage, shipping, and display unit E1 and ensures the shelf SH3 is held in place via interference fit. The walls of the first, second, and fourth legs of the shelf supports SU ₅₀₀ and SU ₆₀₀ prevent substantial back-and-forth and side-to-side movement of the shelf SH ₃ in the X- and Z-directions relative to the other components of the storage, shipping, and display unit E1. In certain embodiments, the shelf SH ₃ is attached to one or more of the shelf supports SU ₅₀₀ and SU ₆₀₀ in any suitable manner, such as any of those referenced above. [0058] The shelf SH ₄ extends between and is supported by the shelf supports SU ₇₀₀ and SU ₈₀₀ . Specifically, the bottom surface of the shelf SH4 engages the inner surfaces 712i and 812i of the first walls 712 and 812 of the first legs 710 and 810 of the shelf supports SU ₇₀₀ and SU ₈₀₀ so the shelf SH ₄ is oriented generally parallel to the X–Z plane. The shelf SH ₄ is sized and shaped so installing the shelf SH ₄ forces the shelf supports SU ₇₀₀ and SU ₈₀₀ away from one another and against the vertical stabilizers V ₁₀₀ –V ₄₀₀ , which in turn forces the vertical stabilizers V ₁₀₀ –V ₄₀₀ against the top support TS. This adds rigidity to the storage, shipping, and display unit E1 and ensures the shelf SH ₄ is held in place via interference fit. The walls of the first, second, and fourth legs of the shelf supports SU ₇₀₀ and SU ₈₀₀ prevent substantial back-and-forth and side-to-side movement of the shelf SH4 in the X- and Z-directions relative to the other components of the storage, shipping, and display unit E1. In certain embodiments, the shelf SH4 is attached to one or more of the shelf supports SU ₇₀₀ and SU ₈₀₀ in any suitable manner, such as any of those referenced above. [0059] The height H _E1 of the storage, shipping, and display unit E1 is generally equal to the sum of the lengths of the vertically aligned legs of the shelf supports. The width WE1 of the storage, shipping, and display unit E1 is generally equal to the lengths of the first and third legs of the shelf supports SU ₁₀₀ , SU ₂₀₀ , SU ₅₀₀ , and SU ₆₀₀ and the lengths of the stretchers ST ₃₀₀ , ST ₄₀₀ , ST ₇₀₀ , and ST ₈₀₀ . The depth D _E1 of the storage, shipping, and display unit E1 is generally equal to the lengths of the first and third legs of the shelf supports SU ₃₀₀ , SU ₄₀₀ , SU ₇₀₀ , and SU ₈₀₀ and the lengths of the stretchers ST ₁₀₀ , ST ₂₀₀ , ST ₅₀₀ , and ST ₆₀₀ . [0060] The storage, shipping, and display unit of the present disclosure solves the above- described problems. A vendor can assemble the storage, shipping, and display unit; load its product directly onto the storage, shipping, and display unit; and ship the storage, shipping, and display unit to the retailer. After receiving the storage, shipping, and display unit (loaded with products), the retailer moves it onto the sales floor. The storage, shipping, and display unit thus acts as a storage unit, shipping container, and display unit for the products. This eliminates excess packaging for the products, thereby lowering shipping costs and reducing waste. This eliminates the need for retailers to transfer the products from their packaging to display units, which saves time and reduces labor costs. This eliminates the need for retailers to purchase, store, set up, and take down reusable display units, which saves time and money. In instances in which the storage, shipping, and display unit is formed from components made of recyclable material, the reduced weight of the display unit reduces freight costs and therefore increases the shipping radius of the display unit. Yet the construction of the display unit renders it rigid so as not to sacrifice performance. It also reduces the cost of the display unit and, since the display unit is recyclable, enables the retailer to recycle the display unit after use rather than ship it back to the vendor. [0061] In other embodiments, some or all of the stretchers nest into and are supported by the shelf supports. In certain of these embodiments, the shelf supports directly contact and directly support one another, and the stretchers directly contact and directly support the shelves while providing rigidity to the frame. For instance, in one of these embodiments, the stretcher ST ₁₀₀ nests within one of the legs of the shelf support SU ₃₀₀ such that the shelf supports SU ₁₀₀ and SU ₂₀₀ directly contact and directly support that leg of the shelf support SU ₃₀₀ . [0062] Figures 6 and 7 show the frame F2 of another embodiment of the storage, shipping, and display unit. While not shown, this embodiment of the storage, shipping, and display unit includes the same base support, top support, vertical stabilizers, and shelves as the storage, shipping, and display unit E1 shown in Figure 3. The frame F2 includes shelf supports SU ₁₁₀₀ , SU ₁₂₀₀ , SU ₁₃₀₀ , SU ₁₄₀₀ , SU ₁₅₀₀ , SU ₁₆₀₀ , SU ₁₇₀₀ , and SU ₁₈₀₀ and stretchers ST ₁₁₀₀ , ST ₁₂₀₀ , ST ₁₃₀₀ , ST ₁₄₀₀ , ST ₁₅₀₀ , ST ₁₆₀₀ , ST ₁₇₀₀ , and ST ₁₈₀₀ . In this example embodiment, the shelf supports SU ₁₁₀₀ –SU ₁₈₀₀ are the same size and shape, and the stretchers ST ₁₁₀₀ –ST ₁₈₀₀ are the same size and shape. [0063] The frame F2 is formed of multiple frame layers L ₁₁ , L ₁₂ , L ₁₃ , and L ₁₄ , each of which includes a spaced-apart pair of the shelf supports SU ₁₁₀₀ –SU ₁₈₀₀ that together support one of the shelves (not shown). A pair of the stretchers ST ₁₁₀₀ –ST ₁₈₀₀ separates consecutive frame layers. In this example embodiment, the pairs of shelf supports are oriented parallel to the pair(s) of shelf supports in the frame layers above and below that given frame layer. Put differently, in this example embodiment the pairs of shelf supports have the same orientation from frame layer to frame layer. [0064] The orientations of the components of the frame F2 are described below with respect to the coordinate system C shown in Figure 3. For clarity, the supports are showed in simplified form in the drawings, though they are generally the same as the support SU shown in Figures 1A and 1B. [0065] The shelf supports SU ₁₁₀₀ and SU ₁₂₀₀ are oriented generally parallel to the Y–Z plane and are spaced-apart in the X-direction. The shelf support SU ₁₁₀₀ is positioned and oriented so its second and fourth legs 1120 and 1140 extend generally vertically in the Y-direction and so its first and third legs 1110 and 1130 extend generally horizontally in the Z-direction. The shelf support SU1200 is positioned and oriented so its second and fourth legs 1220 and 1240 extend generally vertically in the Y-direction and so its first and third legs 1210 and 1230 extend generally horizontally in the Z-direction. [0066] The stretcher ST ₁₁₀₀ is supported by and extends between and connects the shelf supports SU1100 and SU1200. More specifically, the stretcher ST ₁₁₀₀ is positioned with one end above the second leg 1120 of the shelf support SU ₁₁₀₀ and the other end above the fourth leg 1240 of the shelf support SU ₁₂₀₀ . The stretcher ST ₁₁₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₁₁₀₀ is attached to the shelf supports SU ₁₁₀₀ and SU ₁₂₀₀ in any suitable manner, such as any of those referenced above. [0067] The stretcher ST ₁₂₀₀ is supported by and extends between and connects the shelf supports SU ₁₁₀₀ and SU ₁₂₀₀ . More specifically, the stretcher ST ₁₂₀₀ is spaced-apart from the stretcher ST ₁₁₀₀ in the Z-direction and positioned with one end above the fourth leg 1140 of the shelf support SU ₁₁₀₀ and the other end above the second leg 1220 of the shelf support SU1200. The stretcher ST ₁₂₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₁₂₀₀ is attached to the shelf supports SU ₁₁₀₀ and SU ₁₂₀₀ in any suitable manner, such as any of those referenced above. [0068] The shelf support SU ₁₃₀₀ is supported by the stretchers ST ₁₁₀₀ and ST ₁₂₀₀ . More specifically, the shelf support SU ₁₃₀₀ is positioned and oriented so the second leg 1320 of the shelf support SU ₁₃₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 1120 of the shelf support SU ₁₁₀₀ and the fourth leg 1340 of the shelf support SU ₁₃₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 1140 of the shelf support SU ₁₁₀ 0. In this orientation, the first and third legs 1310 and 1330 of the shelf support SU ₁₃₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₁₃₀₀ is oriented generally parallel to the Y–Z plane. In certain embodiments, the shelf support SU ₁₃₀₀ is attached to one or more of stretchers ST ₁₁₀₀ and ST ₁₂₀₀ in any suitable manner, such as any of those referenced above. [0069] The shelf support SU ₁₄₀₀ is supported by the stretchers ST ₁₁₀₀ and ST ₁₂₀₀ . More specifically, the shelf support SU ₁₄₀₀ is positioned and oriented so the second leg 1420 of the shelf support SU ₁₄₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 1220 of the shelf support SU ₁₂₀₀ and the fourth leg 1440 of the shelf support SU ₁₄₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 1240 of the shelf support SU ₁₂₀₀ . In this orientation, the first and third legs 1410 and 1430 of the shelf support SU ₁₄₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₁₄₀₀ is oriented generally parallel to the Y–Z plane. In certain embodiments, the shelf support SU ₁₄₀₀ is attached to one or more of stretchers ST ₁₁₀₀ and ST ₁₂₀₀ in any suitable manner, such as any of those referenced above. [0070] The stretcher ST ₁₃₀₀ is supported by and extends between and connects the shelf supports SU1300 and SU1400. More specifically, the stretcher ST ₁₃₀₀ is positioned with one end above the second leg 1320 of the shelf support SU ₁₃₀₀ and the other end above the fourth leg 1440 of the shelf support SU ₁₄₀₀ . The stretcher ST ₁₃₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₁₃₀₀ is attached to the shelf supports SU ₁₃₀₀ and SU ₁₄₀₀ in any suitable manner, such as any of those referenced above. [0071] The stretcher ST ₁₄₀₀ is supported by and extends between and connects the shelf supports SU ₁₃₀₀ and SU ₁₄₀₀ . More specifically, the stretcher ST ₁₄₀₀ is spaced-apart from the stretcher ST ₁₃₀₀ in the Z-direction and positioned with one end above the fourth leg 1340 of the shelf support SU1300 and the other end above the second leg 1420 of the shelf support SU1400. The stretcher ST ₁₄₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₁₄₀₀ is attached to the shelf supports SU ₁₃₀₀ and SU ₁₄₀₀ in any suitable manner, such as any of those referenced above. [0072] The shelf support SU ₁₅₀₀ is supported by the stretchers ST ₁₃₀₀ and ST ₁₄₀₀ . More specifically, the shelf support SU ₁₅₀₀ is positioned and oriented so the second leg 1520 of the shelf support SU ₁₅₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 1320 of the shelf support SU ₁₃₀₀ and the fourth leg 1540 of the shelf support SU ₁₅₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 1340 of the shelf support SU ₁₃₀₀ . In this orientation, the first and third legs 1510 and 1530 of the shelf support SU ₁₅₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₁₅₀₀ is oriented generally parallel to the Y–Z plane. In certain embodiments, the shelf support SU ₁₅₀₀ is attached to one or more of stretchers ST ₁₃₀₀ and ST ₁₄₀₀ in any suitable manner, such as any of those referenced above. [0073] The shelf support SU ₁₆₀₀ is supported by the stretchers ST ₁₃₀₀ and ST ₁₄₀₀ . More specifically, the shelf support SU ₁₆₀₀ is positioned and oriented so the second leg 1620 of the shelf support SU ₁₆₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 1420 of the shelf support SU ₁₄₀₀ and the fourth leg 1640 of the shelf support SU ₁₆₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 1440 of the shelf support SU ₁₄₀₀ . In this orientation, the first and third legs 1610 and 1630 of the shelf support SU ₁₆₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₁₆₀₀ is oriented generally parallel to the Y–Z plane. In certain embodiments, the shelf support SU ₁₆₀₀ is attached to one or more of stretchers ST ₁₃₀₀ and ST ₁₄₀₀ in any suitable manner, such as any of those referenced above. [0074] The stretcher ST ₁₅₀₀ is supported by and extends between and connects the shelf supports SU ₁₅₀₀ and SU ₁₆₀₀ . More specifically, the stretcher ST ₁₅₀₀ is positioned with one end above the second leg 1520 of the shelf support SU ₁₅₀₀ and the other end above the fourth leg 1640 of the shelf support SU ₁₆₀₀ . The stretcher ST ₁₅₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₁₅₀₀ is attached to the shelf supports SU ₁₅₀₀ and SU ₁₆₀₀ in any suitable manner, such as any of those referenced above. [0075] The stretcher ST ₁₆₀₀ is supported by and extends between and connects the shelf supports SU1500 and SU1600. More specifically, the stretcher ST ₁₆₀₀ is spaced-apart from the stretcher ST ₁₅₀₀ in the Z-direction and positioned with one end above the fourth leg 1540 of the shelf support SU ₁₅₀₀ and the other end above the second leg 1620 of the shelf support SU ₁₆₀₀ . The stretcher ST ₁₆₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST1600 is attached to the shelf supports SU ₁₅₀₀ and SU ₁₆₀₀ in any suitable manner, such as any of those referenced above. [0076] The shelf support SU ₁₇₀₀ is supported by the stretchers ST ₁₅₀₀ and ST ₁₆₀₀ . More specifically, the shelf support SU ₁₇₀₀ is positioned and oriented so the second leg 1720 of the shelf support SU ₁₇₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 1520 of the shelf support SU ₁₅₀₀ and the fourth leg 1740 of the shelf support SU ₁₇₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 1540 of the shelf support SU ₁₅₀₀ . In this orientation, the first and third legs 1710 and 1730 of the shelf support SU ₁₇₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₁₇₀₀ is oriented generally parallel to the Y–Z plane. In certain embodiments, the shelf support SU ₁₇₀₀ is attached to one or more of stretchers ST ₁₅₀₀ and ST ₁₆₀₀ in any suitable manner, such as any of those referenced above. [0077] The shelf support SU ₁₈₀₀ is supported by the stretchers ST ₁₅₀₀ and ST ₁₆₀₀ . More specifically, the shelf support SU ₁₈₀₀ is positioned and oriented so the second leg 1820 of the shelf support SU ₁₈₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 1620 of the shelf support SU1600 and the fourth leg 1840 of the shelf support SU ₁₈₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 1640 of the shelf support SU ₁₆₀₀ . In this orientation, the first and third legs 1810 and 1830 of the shelf support SU ₁₈₀₀ extend generally horizontally in the Z-direction, and the shelf support SU ₁₈₀₀ is oriented generally parallel to the Y–Z plane. In certain embodiments, the shelf support SU ₁₈₀₀ is attached to one or more of stretchers ST ₁₅₀₀ and ST ₁₆₀₀ in any suitable manner, such as any of those referenced above. [0078] The stretcher ST ₁₇₀₀ is supported by and extends between and connects the shelf supports SU ₁₇₀₀ and SU ₁₈₀₀ . More specifically, the stretcher ST ₁₇₀₀ is positioned with one end above the second leg 1720 of the shelf support SU ₁₇₀₀ and the other end above the fourth leg 1840 of the shelf support SU ₁₈₀₀ . The stretcher ST ₁₇₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₁₇₀₀ is attached to the shelf supports SU ₁₇₀₀ and SU ₁₈₀₀ in any suitable manner, such as any of those referenced above. [0079] The stretcher ST ₁₈₀₀ is supported by and extends between and connects the shelf supports SU ₁₇₀₀ and SU ₁₈₀₀ . More specifically, the stretcher ST1800 is spaced-apart from the stretcher ST ₁₇₀₀ in the Z-direction and positioned with one end above the fourth leg 1740 of the shelf support SU ₁₇₀₀ and the other end above the second leg 1820 of the shelf support SU ₁₈₀₀ . The stretcher ST ₁₈₀₀ extends generally horizontally in the X-direction. In certain embodiments, the stretcher ST ₁₈₀₀ is attached to the shelf supports SU ₁₇₀₀ and SU ₁₈₀ 0 in any suitable manner, such as any of those referenced above. [0080] The height (not labeled) of this embodiment of the storage, shipping, and display unit is generally equal to the sum of the lengths of the vertically aligned legs of the shelf supports. The width (not labeled) of this embodiment of the storage, shipping, and display unit is generally equal to the lengths of the stretchers ST _1100– ST ₁₈₀₀ . The depth (not labeled) of this embodiment of the storage, shipping, and display unit is generally equal to the lengths of the first and third legs of the shelf supports SU ₁₁₀₀ –SU ₁₈₀₀ . [0081] In other embodiments, some or all of the stretchers nest into and are supported by the shelf supports. In certain of these embodiments, the shelf supports directly contact and directly support one another, and the stretchers directly contact and directly support the shelves while providing rigidity to the frame. For instance, in one of these embodiments, the stretcher ST ₁₁₀₀ nests within and extends between the legs of the shelf supports SU ₁₃₀₀ and SU ₁₄₀₀ such that the shelf supports SU ₁₁₀₀ and SU ₁₂₀₀ directly contact and directly support those legs of the shelf supports SU ₁₃₀₀ and SU ₁₄₀₀ . [0082] Figures 8 and 9 show the frame F3 of another embodiment of the storage, shipping, and display unit. While not shown, this embodiment of the storage, shipping, and display unit includes the same base support, top support, vertical stabilizers, and shelves as the storage, shipping, and display unit E1 shown in Figure 3. The frame F3 includes shelf supports SU ₂₁₀₀ , SU ₂₂₀₀ , SU ₂₃₀₀ , SU ₂₄₀₀ , SU ₂₅₀₀ , SU ₂₆₀₀ , SU ₂₇₀₀ , and SU ₂₈₀₀ and stretchers ST ₂₁₀₀ , ST ₂₂₀₀ , ST ₂₃₀₀ , ST ₂₄₀₀ , ST ₂₅₀₀ , ST ₂₆₀₀ , ST ₂₇₀₀ , and ST ₂₈₀₀ . In this example embodiment, the shelf supports SU ₂₁₀₀ –SU ₂₈₀₀ are the same size and shape, and the stretchers ST ₂₁₀₀ –ST ₂₈₀₀ are the same size and shape. [0083] The frame F3 is formed of multiple frame layers L ₂₁ , L ₂₂ , L ₂₃ , and L ₂₄ , each of which includes a spaced-apart pair of the shelf supports SU ₂₁₀₀ –SU ₂₈₀₀ that together support one of the shelves (not shown). A pair of the stretchers ST ₂₁₀₀ –ST ₂₈₀₀ separates consecutive frame layers. In this example embodiment, the pairs of shelf supports are oriented parallel to the pair(s) of shelf supports in the frame layers above and below that given frame layer. Put differently, in this example embodiment the pairs of shelf supports have the same orientation from frame layer to frame layer. [0084] The orientations of the components of the frame F3 are described below with respect to the coordinate system C shown in Figure 3. For clarity, the supports are showed in simplified form in the drawings, though they are generally the same as the support SU shown in Figures 1A and 1B. [0085] The shelf supports SU ₂₁₀₀ and SU ₂₂₀₀ are oriented generally parallel to the X–Y plane and are spaced-apart in the Z-direction. The shelf support SU ₂₁₀₀ is positioned and oriented so its second and fourth legs 2120 and 2140 extend generally vertically in the Y-direction and so its first and third legs 2110 and 2130 extend generally horizontally in the X-direction. The shelf support SU ₂₂₀₀ is positioned and oriented so its second and fourth legs 2220 and 2240 extend generally vertically in the Y-direction and so its first and third legs 2210 and 2230 extend generally horizontally in the X-direction. [0086] The stretcher ST ₂₁₀₀ is supported by and extends between and connects the shelf supports SU ₂₁₀₀ and SU ₂₂₀₀ . More specifically, the stretcher ST ₂₁₀₀ is positioned with one end above the fourth leg 2140 of the shelf support SU ₂₁₀₀ and the other end above the second leg 2220 of the shelf support SU ₂₂₀₀ . The stretcher ST ₂₁₀₀ extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₂₁₀₀ is attached to the shelf supports SU ₂₁₀₀ and SU ₂₂₀₀ in any suitable manner, such as any of those referenced above. [0087] The stretcher ST ₂₂₀₀ is supported by and extends between and connects the shelf supports SU ₂₁₀₀ and SU ₂₂₀₀ . More specifically, the stretcher ST ₂₂₀₀ is spaced-apart from the stretcher ST ₂₁₀₀ in the X-direction and positioned with one end above the second leg 2120 of the shelf support SU ₂₁₀₀ and the other end above the fourth leg 2240 of the shelf support SU ₂₂₀₀ . The stretcher ST ₂₂₀₀ extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₂₂₀₀ is attached to the shelf supports SU ₂₁₀₀ and SU ₂₂₀₀ in any suitable manner, such as any of those referenced above. [0088] The shelf support SU ₂₃₀₀ is supported by the stretchers ST ₂₁₀₀ and ST ₂₂₀₀ . More specifically, the shelf support SU ₂₃₀₀ is positioned and oriented so the second leg 2320 of the shelf support SU ₂₃₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 2120 of the shelf support SU ₂₁₀₀ and the fourth leg 2340 of the shelf support SU ₂₃₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 2140 of the shelf support SU ₂₁₀₀ . In this orientation, the first and third legs 2310 and 2330 of the shelf support SU ₂₃₀₀ extend generally horizontally in the X-direction, and the shelf support SU ₂₃₀₀ is oriented generally parallel to the X–Y plane. In certain embodiments, the shelf support SU ₂₃₀₀ is attached to one or more of stretchers ST ₂₁₀₀ and ST ₂₂₀₀ in any suitable manner, such as any of those referenced above. [0089] The shelf support SU ₂₄₀₀ is supported by the stretchers ST ₂₁₀₀ and ST ₂₂₀₀ . More specifically, the shelf support SU ₂₄₀₀ is positioned and oriented so the second leg 2420 of the shelf support SU2400 extends generally vertically in the Y-direction and is positioned above the second leg 2220 of the shelf support SU ₂₂₀₀ and the fourth leg 2440 of the shelf support SU ₂₄₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 2240 of the shelf support SU ₂₂₀₀ . In this orientation, the first and third legs 2410 and 2430 of the shelf support SU ₂₄₀₀ extend generally horizontally in the X-direction, and the shelf support SU ₂₄₀₀ is oriented generally parallel to the X–Y plane. In certain embodiments, the shelf support SU ₂₄₀₀ is attached to one or more of stretchers ST ₂₁₀₀ and ST ₂₂₀₀ in any suitable manner, such as any of those referenced above. [0090] The stretcher ST ₂₃₀₀ is supported by and extends between and connects the shelf supports SU2300 and SU2400. More specifically, the stretcher ST ₂₃₀₀ is positioned with one end above the fourth leg 2440 of the shelf support SU2300 and the other end above the second leg 2420 of the shelf support SU ₂₄₀₀ . The stretcher ST ₂₃₀₀ extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₂₃₀₀ is attached to the shelf supports SU ₂₃₀₀ and SU ₂₄₀₀ in any suitable manner, such as any of those referenced above. [0091] The stretcher ST ₂₄₀₀ is supported by and extends between and connects the shelf supports SU ₂₃₀₀ and SU ₂₄₀₀ . More specifically, the stretcher ST ₂₄₀₀ is spaced-apart from the stretcher ST ₂₃₀₀ in the X-direction and positioned with one end above the second leg 2320 of the shelf support SU ₂₃₀₀ and the other end above the fourth leg 2440 of the shelf support SU ₂₄₀₀ . The stretcher ST ₂₄₀₀ extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₂₄₀₀ is attached to the shelf supports SU ₂₃₀₀ and SU ₂₄₀₀ in any suitable manner, such as any of those referenced above. [0092] The shelf support SU ₂₅₀₀ is supported by the stretchers ST ₂₃₀₀ and ST ₂₄₀₀ . More specifically, the shelf support SU ₂₅₀₀ is positioned and oriented so the second leg 2520 of the shelf support SU ₂₅₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 2320 of the shelf support SU ₂₃₀₀ and the fourth leg 2540 of the shelf support SU ₂₅₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 2340 of the shelf support SU ₂₃₀₀ . In this orientation, the first and third legs 2510 and 2530 of the shelf support SU ₂₅₀₀ extend generally horizontally in the X-direction, and the shelf support SU ₂₅₀₀ is oriented generally parallel to the X–Y plane. In certain embodiments, the shelf support SU ₂₅₀₀ is attached to one or more of stretchers ST ₂₃₀₀ and ST ₂₄₀₀ in any suitable manner, such as any of those referenced above. [0093] The shelf support SU ₂₆₀₀ is supported by the stretchers ST ₂₃₀₀ and ST ₂₄₀₀ . More specifically, the shelf support SU ₂₆₀₀ is positioned and oriented so the second leg 2620 of the shelf support SU ₂₆₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 2420 of the shelf support SU ₂₄₀₀ and the fourth leg 2640 of the shelf support SU ₂₆₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 2440 of the shelf support SU ₂₄₀₀ . In this orientation, the first and third legs 2610 and 2630 of the shelf support SU ₂₆₀₀ extend generally horizontally in the X-direction, and the shelf support SU ₂₆₀₀ is oriented generally parallel to the X–Y plane. In certain embodiments, the shelf support SU ₂₆₀₀ is attached to one or more of stretchers ST ₂₃₀₀ and ST ₂₄₀₀ in any suitable manner, such as any of those referenced above. [0094] The stretcher ST ₂₅₀₀ is supported by and extends between and connects the shelf supports SU ₂₅₀₀ and SU ₂₆₀₀ . More specifically, the stretcher ST ₂₅₀₀ is positioned with one end above the fourth leg 2540 of the shelf support SU2500 and the other end above the second leg 2620 of the shelf support SU ₂₆₀₀ . The stretcher ST ₂₅₀₀ extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₂₅₀₀ is attached to the shelf supports SU ₂₅₀₀ and SU ₂₆₀₀ in any suitable manner, such as any of those referenced above. [0095] The stretcher ST2600 is supported by and extends between and connects the shelf supports SU ₂₅₀₀ and SU ₂₆₀₀ . More specifically, the stretcher ST ₂₆₀₀ is spaced-apart from the stretcher ST ₂₅₀₀ in the X-direction and positioned with one end above the second leg 2520 of the shelf support SU ₂₅₀₀ and the other end above the fourth leg 2640 of the shelf support SU ₂₆₀₀ . The stretcher ST2600 extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₂₆₀₀ is attached to the shelf supports SU ₂₅₀₀ and SU ₂₆₀₀ in any suitable manner, such as any of those referenced above. [0096] The shelf support SU ₂₇₀₀ is supported by the stretchers ST ₂₅₀₀ and ST ₂₆₀₀ . More specifically, the shelf support SU ₂₇₀₀ is positioned and oriented so the second leg 2720 of the shelf support SU ₂₇₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 2520 of the shelf support SU ₂₅₀₀ and the fourth leg 2740 of the shelf support SU ₂₇₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 2540 of the shelf support SU2500. In this orientation, the first and third legs 2710 and 2730 of the shelf support SU ₂₇₀₀ extend generally horizontally in the X-direction, and the shelf support SU ₂₇₀₀ is oriented generally parallel to the X–Y plane. In certain embodiments, the shelf support SU ₂₇₀₀ is attached to one or more of stretchers ST ₂₅₀₀ and ST ₂₆₀₀ in any suitable manner, such as any of those referenced above. [0097] The shelf support SU ₂₈₀₀ is supported by the stretchers ST ₂₅₀₀ and ST ₂₆₀₀ . More specifically, the shelf support SU ₂₈₀₀ is positioned and oriented so the second leg 2820 of the shelf support SU ₂₈₀₀ extends generally vertically in the Y-direction and is positioned above the second leg 2620 of the shelf support SU2600 and the fourth leg 2840 of the shelf support SU ₂₈₀₀ extends generally vertically in the Y-direction and is positioned above the fourth leg 2640 of the shelf support SU ₂₆₀₀ . In this orientation, the first and third legs 2810 and 2830 of the shelf support SU ₂₈₀₀ extend generally horizontally in the X-direction, and the shelf support SU ₂₈₀₀ is oriented generally parallel to the X–Y plane. In certain embodiments, the shelf support SU2800 is attached to one or more of stretchers ST ₂₅₀₀ and ST ₂₆₀₀ in any suitable manner, such as any of those referenced above. [0098] The stretcher ST ₂₇₀₀ is supported by and extends between and connects the shelf supports SU ₂₇₀₀ and SU ₂₈₀₀ . More specifically, the stretcher ST ₂₇₀₀ is positioned with one end above the fourth leg 2740 of the shelf support SU ₂₇₀₀ and the other end above the second leg 2820 of the shelf support SU2800. The stretcher ST2700 extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₂₇₀₀ is attached to the shelf supports SU ₂₇₀₀ and SU ₂₈₀₀ in any suitable manner, such as any of those referenced above. [0099] The stretcher ST ₂₈₀₀ is supported by and extends between and connects the shelf supports SU ₂₇₀₀ and SU ₂₈₀₀ . More specifically, the stretcher ST ₂₈₀₀ is spaced-apart from the stretcher ST ₂₇₀₀ in the X-direction and positioned with one end above the second leg 2720 of the shelf support SU ₂₇₀₀ and the other end above the fourth leg 2840 of the shelf support SU ₂₈₀₀ . The stretcher ST2800 extends generally horizontally in the Z-direction. In certain embodiments, the stretcher ST ₂₈₀₀ is attached to the shelf supports SU ₂₇₀₀ and SU ₂₈₀₀ in any suitable manner, such as any of those referenced above. [00100] The height (not labeled) of this embodiment of the storage, shipping, and display unit is generally equal to the sum of the lengths of the vertically aligned legs of the shelf supports. The width (not labeled) of this embodiment of the storage, shipping, and display unit is generally equal to the lengths of the shelf supports SU ₁₁₀₀ –SU ₁₈₀₀ . The depth (not labeled) of this embodiment of the storage, shipping, and display unit is generally equal to the lengths of the first and third legs of the stretchers ST ₁₁₀₀ –ST ₁₈₀₀ . [00101] In other embodiments, some or all of the stretchers nest into and are supported by the shelf supports. In certain of these embodiments, the shelf supports directly contact and directly support one another, and the stretchers directly contact and directly support the shelves while providing rigidity to the frame. For instance, in one of these embodiments, the stretcher ST ₂₁₀₀ nests within and extends between one of the legs of the shelf supports SU ₂₃₀₀ and SU ₂₄₀₀ such that the shelf supports SU ₂₁₀₀ and SU ₂₂₀₀ directly contact and directly support those legs of the shelf supports SU ₂₃₀₀ and SU ₂₄₀₀ .