Red Head LDT-3840 Large Diameter Tapcon 3/8-Inch by 4-Inch Anchor (50 per Box) Cuts it's Own Threads into Concrete Anchor Bodies are Made of Hardened Carbon Steel and Zinc Plated, Grade 8 Finished Hex Washer Head, with Anti-Rotation Serrations Anchor is Stamped with a Length Identification Code Use Standard Drill Bits