A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 4140-01-422-2226
NSN 5835-00-198-4936
NSN 6610-00-108-9546
NSN 5930-01-381-5350
NSN 6610-01-381-3181
NSN 6240-01-069-9022
NSN 5960-01-195-7590
NSN 5975-00-485-5829
NSN 5945-01-251-9594
NSN 6320-01-643-0850
NSN 5985-00-770-2447
NSN 6610-01-093-4710