BBI Structural Bolt, Heavy Partially Threaded, Measurement System: Imperial, 1-8 Thread, 4-1/2 in Length Under Head, Steel Alloy, Hot Dipped Galvanized, 1-3/4 in Thread Length, Material Specification: ASTM A325 Type 1, Hex Head, 0.627 in Drive, UNC Thread, 0.627 in Head, Hex Drive, 1.022 in Shank