BEST-IN-CLASS CORROSION PROTECTION: 305 Stainless steel combines a polished look with superior protection against rust and corrosion in all exterior projects. These screws have a Square Drive that is easy to use and more durable than Phillips for better efficiency. The Type 17 point and flathead with nibs have been designed to remove material to prevent splitting and ensure a flush counter-sunk finish. SAFE FOR TREATED LUMBER: Recommended for use with ACQ in exterior projects.