A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 2925-01-129-1261
NSN 5965-00-893-6602
NSN 5905-00-562-1734
NSN 6105-00-324-7470
NSN 5935-00-042-6851
NSN 5910-01-541-5950
NSN 7035-01-328-7448
NSN 6650-01-365-1894
NSN 4140-00-763-2325
NSN 6650-01-211-9642
NSN 5945-01-372-2498
NSN 5990-01-303-6110