A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5915-01-304-6915
NSN 6130-00-473-2270
NSN 5930-00-721-0421
NSN 6145-01-448-7819
NSN 6685-01-317-1569
NSN 5985-01-587-7167
NSN 5998-00-445-6466
NSN 5905-01-268-6412
NSN 5920-00-142-9993
NSN 6150-01-565-0931
NSN 5998-01-314-5885
NSN 6685-01-219-3933