A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5910-00-123-5727
NSN 6650-00-382-6080
NSN 2925-01-320-6512
NSN 6105-00-970-9074
NSN 6150-01-327-2569
NSN 6610-01-351-4607
NSN 5950-00-392-9299
NSN 7035-01-422-4642
NSN 5935-01-262-0844
NSN 5855-01-316-9642
NSN 6145-00-582-1301
NSN 6320-01-072-2073