The Strong-Drive SD9 hexagonal head structural screws are tested and approved for use in many of the Simpson Strong-Tie best-selling connectors for both interior and most exterior applications. Optimized heat-treating for ductility and strength. The single-fastener steel-side-plate capacity of the SD9 exceeds the capacity of a 10D common nail. Ideal for use in tight spaces where using a hammer in inconvenient. The hex head virtually eliminates cam-out and helps avoid stripping of the head during installation. The sharp point of the screw eases fast starts, and the patented serrated threads torque for improved drivability.