PRODUCT SPECIFICATIONSPart #: 0000-126668Fastener Type: Square Head Machine BoltSize Description: 5/8"-11 x 4" (PT)Diameter/Nominal Size: 5/8"Length: 4"Wrench Size/Across Flats: 0.906-0.938"Width Across Corners: 1.244-1.326"Head Height: 0.400-0.444"Thread Pitch: 11Thread Pitch Type: CoarseThread Direction: RightThread Coverage: PartialSystem of Measurement: InchGrade: A (2)Material: Low Carbon SteelFinish: Plain Finish (No Plating)Head Type: SquareDrive Type: External SquareStandards Met: A307Average Piece Weight: 0.4008000 lbs.Square head bolts, or square head machine bolts offer a large bearing area for positive gripping; primarily used nowadays for aesthetic projects that create a rustic look or to match existing fasteners; comes in both fully threaded and partially threaded pitches. Square head bolts are sometimes selected over hex heads because the head will fit neatly in a channel.