The Simpson Strong-Tie Exterior Structural Metal Screw, is 16 threads per inch and includes a 5/16" hex head (replacement driver bit — BITHEXR516-134). It is Quik Guard® coated for corrosion protection and has dual hardened heat treatment that improves efficiency. This feature maximizes resilience and reduces the potential for hydrogen embrittlement. To avoid the possibility of corrosion, use only in dry interiors or noncorrosive climates. It Meets ASTM C1513 drill-time performance and is the only fastener load rated for Simpson Strong-Tie® L70Z and LS70Z connectors for use with Trex® Elevations™ steel deck framing applications.