Reverse thread design prevents mushrooming for a clean finish. Engineered for use in exterior applications including classic composite trim and decking, cPVC trim and molding. For use in all applications including pressure treated lumber. RT Composite Trim Screws are self-tapping eliminating pre-drilling, features the W-Cut threads for reduced torque, and available in our Climatek AC257 code approved stainless steel. ESR code approved under ICC Report ESR-3201.