A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5910-01-277-0742
NSN 6685-01-529-1979
NSN 4140-00-045-8117
NSN 7035-01-654-4139
NSN 5835-01-518-4300
NSN 4140-01-459-0829
NSN 5975-00-462-9376
NSN 5950-01-217-1287
NSN 5960-01-500-6615
NSN 5905-01-634-0595
NSN 6150-01-400-4211
NSN 5895-00-679-9479