A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6110-01-408-5621
NSN 6320-01-578-6006
NSN 6150-00-111-7281
NSN 6645-01-633-1852
NSN 6135-01-351-2690
NSN 6240-00-042-7136
NSN 6645-01-099-4322
NSN 5835-01-268-1924
NSN 5935-00-151-4910
NSN 6320-01-583-6809
NSN 5999-01-392-6313
NSN 5998-01-556-4250