A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 4140-01-144-9520
NSN 5855-01-018-1247
NSN 7035-01-110-5745
NSN 5910-01-655-5888
NSN 6105-01-394-2603
NSN 6610-00-404-1287
NSN 5910-01-394-5357
NSN 6130-00-236-7926
NSN 6105-01-546-7832
NSN 5920-01-065-9148
NSN 2925-01-394-1812
NSN 5925-01-633-4041