A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5905-01-295-7591
NSN 5930-01-650-1834
NSN 6105-00-482-2658
NSN 5998-00-456-0864
NSN 6620-01-177-1772
NSN 5930-00-616-1861
NSN 6645-01-539-5922
NSN 6130-00-266-7496
NSN 2925-01-525-8212
NSN 5950-01-416-2971
NSN 6145-01-391-5022
NSN 5965-01-633-8849