A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-01-147-5225
NSN 5975-01-434-7981
NSN 5835-01-547-9631
NSN 5990-01-546-1649
NSN 5998-01-188-7555
NSN 5990-00-112-0689
NSN 6240-01-480-8996
NSN 5915-00-525-5753
NSN 5915-01-011-2135
NSN 5855-00-147-2508
NSN 5935-00-956-8974
NSN 5999-01-052-7352