A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6130-00-737-0459
NSN 6145-00-593-8100
NSN 6130-00-933-9081
NSN 5996-01-535-0963
NSN 6220-01-189-1373
NSN 5920-01-417-1928
NSN 5945-01-589-7804
NSN 5945-01-623-0387
NSN 6135-01-052-9634
NSN 6240-01-555-8365
NSN 6620-01-599-2011
NSN 6645-01-626-3174