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 5855-01-472-3963
NSN 6645-00-171-9639
NSN 5975-00-269-8391
NSN 5996-01-050-3141
NSN 6620-01-039-1105
NSN 5965-01-449-4606
NSN 5910-00-667-7025
NSN 5965-00-404-0486
NSN 5999-00-151-4062
NSN 5935-01-364-9380
NSN 5985-00-143-0008
NSN 5996-01-538-2841