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 6620-01-029-8723
NSN 5835-00-647-2104
NSN 7035-00-185-8683
NSN 6110-01-517-4995
NSN 5965-00-934-3495
NSN 6240-01-080-5797
NSN 5999-01-634-0576
NSN 6240-01-390-6996
NSN 5930-00-479-4114
NSN 6150-00-100-4757
NSN 5945-01-477-2263
NSN 5998-00-763-0326