The Strong-Drive SD Connector screw is specifically designed to replace nails in certain Simpson Strong-Tie connectors and is the only screw approved for that application. The load-rated SD screw has been tested and approved for use in many popular Simpson Strong-Tie products. In certain applications screws are easier and more convenient to install than nails, and the single-fastener load values achieved by the SD screw exceed. In addition, the galvanized coating makes the SD screw ideal for interior and most exterior conditions.