A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5945-00-208-5763
NSN 6610-01-333-2381
NSN 4140-01-296-6167
NSN 5855-01-535-7127
NSN 6110-00-730-6272
NSN 5950-00-867-6897
NSN 5975-01-457-8254
NSN 5920-01-198-6805
NSN 5960-00-930-4458
NSN 6240-00-280-8502
NSN 5950-01-447-6105
NSN 5985-01-412-0252