Milwaukee Thunderbolt 1/2 In. Black Oxide Drill BitMilwaukee 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.