A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5920-01-542-6822
NSN 6240-00-485-6012
NSN 5965-01-486-3564
NSN 6240-00-079-0112
NSN 5985-01-034-8942
NSN 6145-00-138-4036
NSN 5965-00-735-9315
NSN 7035-00-054-3414
NSN 6150-01-120-8487
NSN 5895-01-386-4680
NSN 5915-01-026-1460
NSN 5990-01-633-9503