A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6620-01-643-5531
NSN 6610-01-170-7107
NSN 6685-00-720-3525
NSN 6650-01-420-7388
NSN 6620-01-345-9488
NSN 5998-00-823-1126
NSN 5895-01-383-3625
NSN 6135-00-539-8088
NSN 6130-00-421-2417
NSN 5999-00-518-2817
NSN 6650-01-192-2340
NSN 6145-01-506-0672