A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6685-01-449-1451
NSN 5965-01-388-4181
NSN 5920-01-430-6921
NSN 6105-01-075-3765
NSN 5960-01-462-6267
NSN 7035-01-236-5743
NSN 5930-01-457-9325
NSN 5855-01-010-4921
NSN 5920-00-450-6192
NSN 6135-00-968-8594
NSN 5945-00-156-0781
NSN 4140-01-076-7481