Our THUNDERBOLT® Black Oxide Drill Bit Set offers convenient, heavy-duty performance on the job site. MILWAUKEE® drill bits are designed for extreme durability and long life. The THUNDERBOLT™ web features a thicker core than a standard drill bit to provide ultimate strength and protection against side-load breakage. Our 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° split point tip delivers a precision start and prevents walking for fast, accurate holes. Black oxide drill bits are effective for drilling on curved surfaces. The Milwaukee THUNDERBOLT™ Black Oxide Bits require less effort to drill through metal, wood, and PVC, and are highly recommended for use with portable drills.