A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-01-554-0901
NSN 4140-00-053-9499
NSN 5925-01-268-0426
NSN 6110-01-154-7066
NSN 6650-01-127-9518
NSN 5895-01-562-1143
NSN 5999-01-239-3432
NSN 5960-00-570-6986
NSN 5855-01-293-7444
NSN 5835-00-065-6757
NSN 5905-01-333-4928
NSN 6130-01-495-4632