A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5950-00-769-0220
NSN 6220-00-943-1948
NSN 5945-01-591-9646
NSN 6320-01-265-0665
NSN 5925-00-606-6529
NSN 5960-01-015-0381
NSN 6610-01-513-1903
NSN 5960-00-074-3727
NSN 5930-00-362-6737
NSN 6240-01-347-2577
NSN 5855-01-163-8152
NSN 5935-01-174-0685