IRWIN Tools 1870964 Impact Performance Series Black Oxide 135-Degree Split-Point Drill Bit, 1/2-Inch Built for maximum durability and long life with impact drivers One-piece construction withstands higher torque loads than standard quick-change bits 135Degree split point eliminates "walking" and drills with less effort Made from premium high speed steel with black oxide finish for added corrosion resistance Black oxide finish resists corrosion and increases life of bit