Category: Lag bolts, Dimensional standard: ASME B18.2.1, Head style: Hex , Material: Stainless steel, Grade: 18-8, Diameter: 1/4", Width across the flats: 7/16", Head height: 11/64", Drive type: External hex, Finish: ASTM A380, Thread requirements: The minimum thread length must be equal to one half the nominal Screw length plus ½, or 6 inch, whichever is shorter. Screws too short to conform to this formula must be threaded as close to the head as possible.