The RT Composite Trim's reverse thread design prevents mushrooming to create an even surface and the small trim head provides a clean finished look. The Zip-Tip allows for one step installation with no pre-drilling and the star drive eliminates stripping for improved productivity. Climatek corrosion resistant coating is ground contact lumber approved. Reverse thread design - prevents mushrooming to create an even surfaceTrim head - provides a clean finished lookW-Cut - low installation torque allows for fast driving and ease of installStar drive - eliminates stripping for improved productivityESR-3201 Approved - Approved for Trim application