A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6610-01-151-9454
NSN 5985-00-116-7476
NSN 6135-01-655-1759
NSN 7035-01-435-7962
NSN 6220-01-007-9988
NSN 6145-01-490-6991
NSN 6620-01-183-5329
NSN 5945-00-446-6570
NSN 2925-01-199-7394
NSN 5945-00-269-5375
NSN 6620-01-411-5750
NSN 5920-01-485-2082