5/16 x 1 1/4 Hex Lag Screw Zinc Plated . Hex Lag Screws are manufactured from low carbon steel to meet SAE J429 Grade 1. Lag screws longer than 12 inches will have a minimum thread length of 50% of the screw length up to a maximum of 8 inches. Zinc plated material will meet or exceed ASTM F1941. Hot-Dip Galvanized material will meet or exceed ASTM A153. Typical hardness is HRB 70-100. Tensile strength (not pull out) will meet a minimum of 60,000 psi.