A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-01-535-6925
NSN 6620-01-152-0936
NSN 5996-01-250-3912
NSN 5999-01-613-0069
NSN 5945-01-119-5402
NSN 7035-01-438-2108
NSN 5945-00-018-4543
NSN 5999-00-383-3381
NSN 6145-01-441-1201
NSN 6610-01-441-8364
NSN 6320-00-036-3688
NSN 5925-01-534-4866