Zenith Decking Screws are a self-drilling Type 17 screw specifically designed for decking applications. our stainless steel screws are made from 304-grade stainless steel for superior corrosion resistance and are coped for a flush finish, making them perfect for outdoor use. The square drive ensures that the screwdriver sits firmly in the head of the screw to avoid any chance of cam-out when tightening.304 grade stainless steel for superior corrosion resistanceCopes with the expansion and contraction of decking boardsCountersunk ribbed head for flush finishSquare drive for positive bit engagement and resistance to cam-out