A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5965-00-161-6429
NSN 6220-00-900-5302
NSN 6145-00-683-5353
NSN 5960-00-834-0571
NSN 4140-01-435-6198
NSN 5935-01-113-1615
NSN 7035-00-088-7355
NSN 6610-01-032-5335
NSN 5925-01-442-3792
NSN 7035-00-941-4949
NSN 5965-01-555-8007
NSN 5998-01-517-5255