A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5855-00-494-9581
NSN 5920-01-197-5097
NSN 5999-01-528-6795
NSN 4140-00-570-3440
NSN 5998-01-212-4155
NSN 2925-01-376-6760
NSN 6150-01-168-1556
NSN 6110-01-094-8576
NSN 5930-01-377-2647
NSN 5935-01-069-3867
NSN 6240-00-871-8798
NSN 5930-01-634-0659