A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6130-01-333-0965
NSN 5905-01-107-0311
NSN 7035-00-731-8729
NSN 6105-00-722-3129
NSN 6610-01-184-8950
NSN 5935-01-279-5177
NSN 6650-00-734-3985
NSN 6240-01-426-2190
NSN 2925-01-171-2511
NSN 5950-00-857-9438
NSN 2925-00-127-7828
NSN 5935-01-153-8302