A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5945-01-649-0011
NSN 6685-00-213-8451
NSN 6130-01-326-4680
NSN 6145-01-254-8502
NSN 6620-00-708-1417
NSN 6145-01-420-7452
NSN 5975-01-444-6362
NSN 6130-01-045-7968
NSN 5895-01-411-7220
NSN 6150-01-592-2252
NSN 5990-00-011-2994
NSN 5855-01-169-9228