Self Piercing Sheeters are engineered to fasten thin pieces of metal to wood, fiberglass or metal primarily through a pre-drilled, or own generated hole in light gauge metal. Perfect for roofing construction, the featured neoprene washer provides a water-tight seal, and prevents corrosion between surfaces. These screws have a ceramic finish that exceeds the 1000 hour salt spray test, and is recommended for use for treated lumber.