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 6645-00-010-3054
NSN 5895-01-561-1913
NSN 5998-01-452-2912
NSN 6145-00-097-9437
NSN 6240-00-646-6931
NSN 5925-01-010-2925
NSN 5999-00-528-2263
NSN 5965-00-011-6742
NSN 6105-01-260-0177
NSN 6135-01-199-1185
NSN 5960-01-604-1158
NSN 5996-01-232-7395