A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5996-00-114-0233
NSN 5855-01-547-6540
NSN 5960-00-636-4834
NSN 6135-01-196-7399
NSN 5960-01-415-3574
NSN 6620-01-553-7296
NSN 5945-00-263-1511
NSN 6685-01-394-5861
NSN 5990-01-277-9753
NSN 6240-00-643-4532
NSN 6145-01-297-9585
NSN 5975-01-462-5846