A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5945-01-133-3627
NSN 6610-01-042-0917
NSN 4140-01-243-1658
NSN 5975-01-129-6217
NSN 5945-01-320-6907
NSN 6240-01-272-5893
NSN 6135-01-415-1163
NSN 6610-01-630-5515
NSN 5985-00-918-7122
NSN 5895-01-171-7250
NSN 6105-00-915-4590
NSN 6145-00-387-5459