Carriage Bolt Inch Neck Type Square Basic Material Steel Material Grade Grade A Fastener Finish Hot Dipped Galvanized Dia/Thread Size 1/4 In.-20 Fastener Length 3 1/2 in Fastener Thread Direction Right Hand Fastener Thread Type UNC (Coarse) ASME B18.5 Drill Size 1/4 in Head Dia 0.563 in to 0.594 in Head Height 9/64 in Head Type Round Square Height 0.125 in to 0.156 in Square Width 0.245 in to 0.260 in Tensile Strength 74 000 psi For Use With Grade 2 Galvanized Nuts