BBI Structural Bolt, Heavy Partially Threaded, Measurement System: Imperial, 1/2-13 Thread, 2 in Length Under Head, Steel Alloy, Hot Dipped Galvanized, 1 in Thread Length, Material Specification: ASTM A325 Type 1, Hex Head, 0.323 in Drive, UNC Thread, 0.323 in Head, Hex Drive