A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 6150-01-258-4036
NSN 6685-01-144-5913
NSN 5925-01-350-5553
NSN 6610-01-382-7894
NSN 5960-00-822-9519
NSN 5935-01-271-2322
NSN 6240-01-585-1086
NSN 5998-00-794-6225
NSN 6645-01-023-8020
NSN 5950-00-354-3316
NSN 6145-01-524-9923
NSN 6620-00-426-6884