A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5920-01-599-2455
NSN 5855-01-658-4510
NSN 5835-01-355-3654
NSN 5999-01-633-0365
NSN 5990-01-644-1441
NSN 5920-01-501-5593
NSN 5998-01-573-3301
NSN 5945-00-419-0184
NSN 5905-01-431-3750
NSN 5960-00-721-1744
NSN 6110-00-794-9739
NSN 6110-01-331-4017