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 6645-01-535-7136
NSN 6610-00-778-9039
NSN 6220-01-416-2867
NSN 5925-01-060-5265
NSN 5999-01-406-4911
NSN 6110-01-210-4164
NSN 5990-01-373-3104
NSN 5855-01-316-3634
NSN 6240-01-633-9357
NSN 6135-00-164-8780
NSN 7035-01-251-5764
NSN 5855-00-832-9341