Bar Material: 40Cr or 45# steel, round corner 5mm radiusHelix Plate material conforms to ASTM A36 hot rolled platehelices thickness are available in 3/8” and 1/2”All helix leading edges sharpened and rock cut and 45 degrees.Corrosion protection to conform to ASTM A153 standard for hot dipped zinc coatingA better conventional solid steel extra high strength helical screw pileWelded coupling for greater strength. Eliminates shaft heat damage caused by upset coupling process