To prevent a coated part of a case from being damaged and to provide a structure suitable for recycling by solving the problems that recoating and labor for the recoating are required at the time of recycling when the coated part coated on the surface of a case, especially on the surface of the body section of the case is injured in the case when a caution label has fallen off or slipped out of place or that the coated part is apt to be injured when a polyhedron part is fitted into a tool.

The case 1 has a centroclinal head part 3, the polyhedron part 4 formed at the periphery of the centroclinal head part 3, the cylindrical body section 5. A projection 7 projecting in a side direction is provided in the vicinity of the boundary between the polyhedron part 4 and the body section 5, and the caution label 6 is stuck on the periphery of the body section 5. The projection 7 functions as a stopper for the caution label 6 so as to prevent falling-off or slippage of the caution label 6. Further, the projection 7 functions as a stopper for positioning the tip end 13 of the tool.