A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-00-027-7508
NSN 6650-01-633-5160
NSN 5975-01-417-1752
NSN 6610-00-925-5064
NSN 5915-01-387-5302
NSN 7035-00-252-7467
NSN 5999-01-519-5914
NSN 5855-00-631-4565
NSN 6130-00-233-6197
NSN 6145-00-489-3574
NSN 6130-01-656-7451
NSN 5965-00-811-3793