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 6320-01-531-4997
NSN 6620-01-302-1537
NSN 6105-01-263-0727
NSN 5855-01-429-8702
NSN 6620-00-104-9722
NSN 6620-01-203-3526
NSN 6620-00-468-9824
NSN 2925-01-187-5480
NSN 5920-01-546-0492
NSN 5855-00-915-7942
NSN 5996-00-826-3198
NSN 5996-01-164-6758