A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5915-01-549-6634
NSN 5925-00-875-1296
NSN 5975-00-520-2906
NSN 6320-00-194-4252
NSN 6620-01-141-5747
NSN 5985-01-623-0661
NSN 4140-00-353-5757
NSN 6610-01-462-5980
NSN 5985-01-406-3261
NSN 5945-01-643-9666
NSN 5905-01-472-2366
NSN 5855-00-466-2309