US Patent 8070404 Bonding fastener assembly for electrical grounding

A fastener assembly comprising a fastener with a head having a first surface and second surface, and a shaft extending from the second surface of the head. An annular washer is rotatably disposed about the shaft and rotatable relative to the second surface of the fastener head. The washer has an inner diameter, an outer diameter, a first surface and a second, the first surface being positioned adjacent to the second surface of the head. A plurality of identical conical projections extend out from the second surface of the washer and are formed integrally therewith.