A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5835-01-058-6280
NSN 6130-01-421-1539
NSN 5960-00-145-5378
NSN 5950-01-117-4992
NSN 5905-00-211-0230
NSN 6110-00-081-0927
NSN 5910-01-355-0345
NSN 5998-01-227-2764
NSN 5998-01-453-0722
NSN 6610-01-033-1748
NSN 6650-00-511-8673
NSN 6650-01-134-6186