A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6645-00-411-3733
NSN 5905-01-116-8336
NSN 5965-01-279-8073
NSN 6610-01-110-0195
NSN 6135-01-113-1507
NSN 5915-01-476-7124
NSN 7035-01-566-1592
NSN 6620-01-054-9346
NSN 5835-01-291-5405
NSN 5998-01-338-3792
NSN 5925-00-647-3469
NSN 5915-01-121-3453