Peco Hex Bolt, Measurement System: Imperial, 1/2-13 Thread, 2-1/2 in Length Under Head, 5 Grade, Carbon Alloy Steel, Zinc Plated, USS Thread, 0.302 to 0.323 in H x 0.84 to 0.866 in W Head, Hex Head, 120000 psi Tensile Strength, Material Specification: ASME B18.2.1-1996, 1-1/4 in Minimum Thread Length, Rockwell C25 to C34 Hardness