A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5990-00-949-0166
NSN 6645-01-361-4813
NSN 6135-01-495-0933
NSN 7035-00-349-8571
NSN 5960-01-537-8161
NSN 5945-00-614-1556
NSN 6610-01-534-2147
NSN 5945-01-528-2444
NSN 5930-01-649-2165
NSN 5915-01-399-7278
NSN 4140-00-519-2781
NSN 5998-00-206-6613