A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6135-00-767-0331
NSN 6240-00-066-0714
NSN 2925-01-106-8871
NSN 6650-01-384-1657
NSN 5975-00-199-4956
NSN 6145-01-063-6486
NSN 6685-01-441-1391
NSN 5999-00-168-9398
NSN 6110-01-367-6526
NSN 6645-01-526-0379
NSN 6610-00-466-3104
NSN 6130-01-461-9748