Milwaukee Thunderbolt Black Oxide jobber length 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 protect against side-load breakage. A specially designed parabolic flute form clears chips and debris fast to keep the bit cool. The 135 degree split point tip delivers a precision start and prevents walking for fast, accurate holes. Effective for drilling on curved surfaces, Milwaukee Thunderbolt Black Oxide bits require less effort to drill through metal, wood and PVC, and are highly recommended for use with portable drills.