A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5985-00-538-7634
NSN 6150-01-331-9860
NSN 5930-00-582-1730
NSN 5998-01-027-4331
NSN 6650-00-150-1761
NSN 5855-00-885-8452
NSN 5910-00-679-9556
NSN 5965-00-845-1905
NSN 5975-01-461-6856
NSN 5985-01-246-8302
NSN 5990-01-211-6136
NSN 5925-01-322-7930