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 5935-00-682-0568
NSN 6110-00-294-0123
NSN 5998-01-430-8908
NSN 5950-00-153-1959
NSN 7035-00-513-9764
NSN 5990-01-186-8310
NSN 5996-01-482-0178
NSN 6620-00-104-6937
NSN 6610-00-450-0796
NSN 6220-01-477-3105
NSN 4140-00-104-7323
NSN 6145-01-069-9332