PURPOSE: To improve withstand load performance, to bring an advantageous state for carrying in light weight and without a bulk, to generate no slide at the time of transport and to ensure safety against a shock.

CONSTITUTION: Inclined side faces 3 in the longitudinal direction expanded toward a lower section and inclined side faces 4 in the short side direction are formed on the periphery of a slender round and long-sized receiving surface 2, and a beltlike collar 5 in the longitudinal direction and a beltlike collar 6 in the short side direction are formed in the horizontal direction from the lower ends of the inclined side faces 3, 4. Ribs 13 projected from external surfaces are shaped to the inclined side faces 3, and a sheet-shaped non-slip layer 6 having a granulated sugar-shaped surface is bonded with the top face of the receiving surface 2 and the underside of the beltlike collar 5.