A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6135-01-322-4655
NSN 6220-01-549-9584
NSN 6130-01-204-8215
NSN 5999-01-141-6859
NSN 5905-01-654-1808
NSN 5855-00-149-0766
NSN 5915-00-722-7928
NSN 6220-01-503-2269
NSN 6110-01-591-2043
NSN 5975-01-535-8033
NSN 6320-00-937-5625
NSN 5998-01-058-8362