A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6650-01-313-8949
NSN 6685-01-583-8753
NSN 6620-00-424-4335
NSN 5999-01-242-0304
NSN 5945-01-131-2451
NSN 5985-01-097-7758
NSN 5895-01-411-5138
NSN 5925-01-619-2113
NSN 2925-01-633-4048
NSN 6220-01-042-9773
NSN 5925-01-167-8144
NSN 5935-01-172-5364