A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6135-01-247-5660
NSN 5998-01-513-3988
NSN 7035-00-020-2227
NSN 6320-01-029-4220
NSN 5910-01-141-7666
NSN 5945-00-683-5846
NSN 6110-01-407-0598
NSN 5996-01-104-1851
NSN 5905-00-204-6499
NSN 6105-00-725-4104
NSN 6105-01-555-7874
NSN 6620-01-391-7331