A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5905-01-292-1546
NSN 5835-00-518-4507
NSN 6130-01-030-4117
NSN 6135-00-309-0074
NSN 6145-01-369-4873
NSN 5945-01-336-7444
NSN 5965-00-071-0562
NSN 5998-01-208-7843
NSN 4140-00-654-9146
NSN 5905-01-507-5412
NSN 5945-00-542-1281
NSN 6650-00-028-2218