A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6130-01-600-5064
NSN 5999-01-199-9143
NSN 4140-00-905-6570
NSN 7035-01-214-5171
NSN 6150-01-154-9686
NSN 6320-01-512-2031
NSN 5905-00-728-7529
NSN 5985-00-159-6213
NSN 5935-01-388-1002
NSN 5999-00-466-3226
NSN 5960-00-577-6942
NSN 5960-01-369-6898