A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-00-894-1644
NSN 6610-00-270-9974
NSN 5855-01-460-9954
NSN 7035-01-658-1623
NSN 4140-01-303-5103
NSN 5965-01-341-8746
NSN 5998-00-273-3980
NSN 6240-01-026-9289
NSN 5930-00-707-3395
NSN 5985-01-420-4040
NSN 5996-01-443-7622
NSN 5935-01-042-6332