An item generally round in shape and usually having a centrally located hole. It has at least one flat bearing surface. It is made of precious or semi-precious gem (ruby, sapphire and the like), natural or synthetic. It is intended for use in precision instruments, meters, timing devices, clocks, and the like.
0.0125 inches nominal overall width, 0.0500 inches nominal body outside diameter, 0.0048 inches nominal hole diameter, 0.0048 inches nominal cup diameter, mil-b-27497 mil spec all material responses overall material document and classification