Our self tapping screw is a very heavy duty hex head small lag screw with a washer. The washer has a rubber gasket on it because it can be used for steel roofing and the rubber washer prevents water from entering a building. However, we mainly use these for our fold down cleats because they attach very nicely without the need to drill a pilot hole in most materials. Be very aware of your material because in some cases you may split the wood. This screw will tap into 2x6 decking or correct deck with no problem with about 1-1/2" or more spacing to the edge of the material.