A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6320-00-925-0558
NSN 5965-01-304-3638
NSN 6645-01-435-6373
NSN 5999-01-122-2351
NSN 6650-00-346-8672
NSN 5910-01-496-6654
NSN 5999-01-258-5693
NSN 6135-01-156-4627
NSN 5855-01-411-3360
NSN 5905-00-584-1302
NSN 6645-00-427-8889
NSN 6105-01-057-1144