Features and Benefits: Bit is constructed of M-2 high speed steel for the best combination of strength, heat resistance and wear resistance; For general use in wood, metal and plastic; Black oxide coating resists corrosion; 135 degree split point ensures a true start and eliminates bit walking; IRWIN offers a complete line of Metal Twist Drill Bits, including Black Oxide, Turbo Point, Titanium Nitride, and Cobalt Drill Bits.. Black oxide coating for added corrosion resistance and added lubricity.