High tempered aluminum for maximum durability with deep and long wearing 1/8" graduations on face and back and a protective lacquered coating resists corrosion. Lumber scale, decimal equivalent table, metric conversion table, formula for squaring a foundation, 45, 60 degree,30#&176, angle markings, volume and area formulas , wood screw gauge table, nail sizes and depth scale. Tables and information imprinted on both sides of square.