SPAX HCR Assortment Kit (High Corrosive Resistant) Check out our Threads!! Our patented thread technology allows the screw to be driven faster, is easier to install, and reduces splitting in wood. Let SPAX take some of the hassle out of your next project. No required pre-drilling in wood. Be more efficient on the job by eliminating time consuming steps with self drilling SPAX. Heat Treated Grade 5 Durability. Subjecting the screw to heat treating gives greater strength and reduces breakage. Patented MULTIhead countersinks the screw head flush in wood. Keep a smooth surface on your project for greater design and functional qualities. Enjoy a variety of screws for different projects. There when you need them.