A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5835-01-442-6482
NSN 6240-01-516-6243
NSN 5930-01-375-0229
NSN 5920-01-029-4538
NSN 6135-01-222-0703
NSN 6610-01-234-9098
NSN 5999-01-519-7910
NSN 5960-00-201-5265
NSN 6150-00-846-6994
NSN 7035-00-238-3662
NSN 6150-01-474-3954
NSN 5935-00-145-9499