A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5996-01-381-6564
NSN 6135-01-173-2588
NSN 5895-01-417-8721
NSN 6650-00-266-6808
NSN 5925-00-318-3023
NSN 7035-00-574-4223
NSN 6645-01-432-7943
NSN 5960-01-346-6002
NSN 6320-01-476-7702
NSN 6220-01-025-0482
NSN 6610-01-479-0466
NSN 4140-01-513-0132