The IRWIN® Tools 3018010 TurboMax Titanium Nitride Coated 18-Piece Drill Bit set in Pro Case comes with 18 twist drill bits ranging from 1/16-Inch to 1/2-Inch in diameter. The Turbomax Titanium Nitride Coated bits feature IRWIN®'s patented Turbomax tip that provides bur free holes, exact centering and no walking on flat and curved surfaces. Drilling on corved surfaces, like pipe, can be a difficult task to drill exactly where you want to, but the Turbomax tip takes the challange out of that process by starting directly on center. These bits also have a Titanium Nitride Coated for 6-times longer life than trditional high speed steel bits. The drill bits also have a reinforced web for added strength and durability. All of the drill bits in the set that are 3/16-Inch in diameter and larger have 3-flatted shanks to help reduce splippage by having better chuck grip. The TurboMax Titanium Nitride Coated drill bits combine the speed and durabilty that the user is looking for in drill bits.