Used for attaching metal to heavy section steel (Max. 12mm) without the need to pre-drill a hole. NOTE: Partially threaded. Exterior plating gives a reliable and durable corrosion resistant coating which resists 1,000 hours salt-spray" Thread Dia. mm: M5.5 Length mm: 38 Thread Length mm: N/A Thread Type: Metric with V Flutes & Torque Relieving Slash Head Type: Hex Head Dia. mm: N/A Finish: Exterior (Silver Organic) Material: Case & Core Hardened Carbon SteelSize 5.5 x 38 - 100 Pieces Timco Self-Drilling Screws - Hex - For Heavy Section Steel - Exterior in Silver