A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5925-00-248-5734
NSN 5915-00-776-6496
NSN 5950-01-371-3688
NSN 5998-00-520-2705
NSN 5960-00-410-3500
NSN 6240-00-526-0243
NSN 5930-01-221-6079
NSN 6145-00-239-1304
NSN 7035-01-344-8708
NSN 5835-01-163-4215
NSN 6620-01-174-4956
NSN 7035-01-062-0184