A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5925-00-100-0102
NSN 5925-00-050-1297
NSN 6650-01-398-1117
NSN 5925-01-442-5795
NSN 5960-01-015-2610
NSN 5950-00-133-8953
NSN 6610-00-834-0713
NSN 5925-00-456-0651
NSN 5975-00-009-8718
NSN 5925-01-346-1795
NSN 5910-01-521-2872
NSN 5835-00-683-4612