A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6240-00-239-0159
NSN 5965-01-285-2133
NSN 6650-00-984-5340
NSN 5915-01-555-8081
NSN 6130-00-181-1787
NSN 6110-01-024-2899
NSN 6105-01-178-7893
NSN 5999-00-564-4201
NSN 5990-01-453-3552
NSN 7035-01-476-7787
NSN 6620-01-118-2337
NSN 5998-01-646-8700