A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-01-415-5150
NSN 5990-01-476-9956
NSN 6110-01-255-1712
NSN 5930-01-200-5897
NSN 6650-01-449-1413
NSN 2925-01-323-4235
NSN 7035-01-091-7481
NSN 5990-00-719-4947
NSN 5975-00-058-5241
NSN 5999-01-148-2225
NSN 6145-01-660-1751
NSN 5835-01-606-8768