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.
used on a pivot in a synchro; 0.09 in o.d.; 0.02 in. i.d.; saphire spun in brass special features