A washer or cone or disk shape with a centrally located hole, designed to accommodate a flat or oval head screw and provide additional bearing area on the material being fastened. It may or may not have a flush flange feature.
NSN 6130-00-812-2357
NSN 6105-01-009-1456
NSN 5990-01-145-2878
NSN 6650-00-567-0715
NSN 7035-01-222-8090
NSN 5985-01-599-2249
NSN 5935-01-137-2281
NSN 6220-01-557-3313
NSN 5999-01-189-7989
NSN 6240-00-055-2141
NSN 5835-01-593-7579
NSN 6130-01-570-2472