Milwaukee S&D Black Oxide drill bits are designed for extreme durability and long life. A specially designed parabolic flute form clears chips fast. while the 3-Flat Secure-Grip shank holds the bit firmly in the drill chuck. The 135 degree split point tip delivers a precision start and prevents walking for fast. accurate holes. Effective for drilling on curved surfaces. Milwaukee Black Oxide bits require less effort to drill through metal. wood and PVC. and are highly recommended for use with portable drills.