A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6685-01-605-2959
NSN 5855-01-068-3683
NSN 5999-01-022-9600
NSN 6220-00-679-5629
NSN 6320-01-418-2611
NSN 5910-01-181-2708
NSN 6135-01-020-1967
NSN 6685-00-983-7541
NSN 6650-01-354-9227
NSN 5985-01-469-5784
NSN 5975-01-445-6915
NSN 5990-01-309-3740