A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6130-01-039-6571
NSN 5999-00-079-1911
NSN 5930-00-146-0092
NSN 5965-00-170-5254
NSN 6130-01-521-2983
NSN 6320-00-389-4756
NSN 5910-01-627-3989
NSN 6130-00-699-8134
NSN 6220-01-034-1231
NSN 6650-01-378-6868
NSN 6150-01-442-6055
NSN 5835-01-464-2662