A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6610-01-029-7544
NSN 5905-00-506-6606
NSN 6620-01-120-9847
NSN 6685-01-022-8479
NSN 5910-01-199-0256
NSN 5999-00-879-1328
NSN 6320-00-004-9158
NSN 6610-00-719-9774
NSN 5945-00-281-1351
NSN 5935-01-265-1111
NSN 5910-01-576-3178
NSN 4140-01-116-1864