A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6110-01-633-9660
NSN 4140-01-558-8059
NSN 6685-01-536-5460
NSN 5930-00-347-1700
NSN 5975-00-061-7035
NSN 5998-01-556-0196
NSN 5905-01-380-1153
NSN 5975-01-576-5660
NSN 5925-00-925-2164
NSN 6135-01-365-2707
NSN 6685-01-231-9583
NSN 5960-00-709-2330