• #1 Square drive Type 17• Self-countersinking bugle head sets flush with work surface• Square Drive recess is deep and cleanly formed — eliminates driver bit cam-out• Precision machined self-drilling point drills its way into all types of wood by removing material during penetration• Self-tapping coarse threads are uniformly sharp — require less driving torque• Coated with non-stick clear, dry lubricating film to enhance drivability• Engineered expressly for building cedar and redwood decks