Milwaukee Thunderbolt Black Oxide Drill Bit Set 29 pc.The MILWAUKEE Thunderbolt Black Oxide Jobber length drill bits are designed for extreme durability and long life. The Milwaukee Thunderbolt web features a thicker core than a standard drill bit to provide ultimate strength and protection against side load breakage. A specially designed parabolic flute form clears chips and debris fast to keep the bit cool. The 135 Split Point tip starts on contact to keep the bit from walking for fast, accurate holes.