A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-01-632-0969
NSN 5975-01-209-6806
NSN 5935-01-264-2141
NSN 6150-00-319-5974
NSN 6220-00-233-9279
NSN 6620-00-199-8734
NSN 6105-00-288-5872
NSN 6105-01-009-1456
NSN 6130-00-840-8886
NSN 6105-01-061-2409
NSN 6110-01-511-3717
NSN 6620-00-224-7739