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 6110-01-429-2358
NSN 5990-01-390-2177
NSN 2925-00-254-9776
NSN 5920-01-493-6191
NSN 5945-00-318-5934
NSN 5945-01-318-3364
NSN 5950-01-048-4103
NSN 5915-00-255-2057
NSN 6130-01-183-5502
NSN 5950-01-435-6190
NSN 6135-00-683-0536
NSN 5985-01-094-5647