Carriage Bolt, Inch, Neck Type Square, Basic Material Steel, Material Grade Grade A, Fastener Finish Hot Dipped Galvanized, Dia./Thread Size 5/16 In.-18, Fastener Length 4 in, Fastener Thread Direction Right Hand, Fastener Thread Type UNC (Coarse), ASME B18.5, Drill Size 21/64 in, Head Dia. 0.688 in, Head Height 11/64 in, Head Type Round, Square Height 0.156 in, Square Width 0.307 in, Tensile Strength 74,000 psi, For Use With Grade 2 Galvanized Nuts, Package Quantity 50