A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5925-01-379-7734
NSN 6650-01-557-4143
NSN 7035-01-218-4233
NSN 6130-00-847-8040
NSN 4140-01-442-4675
NSN 5999-01-134-0650
NSN 5996-00-243-6962
NSN 5999-00-768-0608
NSN 5950-01-629-6494
NSN 6220-01-551-1032
NSN 5985-01-025-7235
NSN 5930-00-841-8546