A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5930-01-172-2779
NSN 5999-01-055-4306
NSN 5935-01-193-0240
NSN 5945-00-540-1052
NSN 6220-01-365-5606
NSN 5999-01-031-7533
NSN 5915-01-624-8527
NSN 6105-01-426-3174
NSN 5960-01-058-8582
NSN 6620-00-104-6937
NSN 6650-00-989-6991
NSN 5996-01-633-7979