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 5935-01-037-7202
NSN 6135-01-398-5922
NSN 6135-00-016-0071
NSN 6135-00-756-6149
NSN 5960-00-443-1483
NSN 6145-00-145-3484
NSN 5835-00-170-5238
NSN 5930-01-054-3868
NSN 2925-01-448-2880
NSN 6110-00-246-3941
NSN 5945-00-394-2754
NSN 6135-00-738-5571