Carriage Bolt, Inch, Neck Type Square, Basic Material Steel, Material Grade Grade A, Fastener Finish Zinc Plated, Dia./Thread Size 1/2 In.-13, Fastener Length 4 in, Fastener Thread Direction Right Hand, Fastener Thread Type UNC (Coarse), ASME B18.5, Drill Size 1/2 in, Head Dia. 1.032 in to 1.094 in, Head Height 17/64 in, Head Type Round, Square Height 0.250 in to 0.281 in, Square Width 0.492 in to 0.515 in, Tensile Strength 74,000 psi, For Use With Grade 2 Zinc Nuts, Package Quantity 10