A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6105-01-142-6179
NSN 5925-00-611-4120
NSN 5985-01-463-3283
NSN 5930-01-020-4717
NSN 5905-00-829-2177
NSN 5855-00-991-0096
NSN 5990-01-425-2175
NSN 6105-01-204-8736
NSN 5960-01-388-4951
NSN 5965-01-534-9961
NSN 5945-00-626-7657
NSN 6240-00-104-4662