TurboMax Straight Shank Drill Bit, is 15/32-inch diameter, 3-pack. The Irwin TurboMax revolutionary Jet Point tip stays sharper longer. Independent tests show TurboMax drills almost twice as many holes as Bullet and nearly 1-1/3-times more holes than Sidewinder. Irwin tools are made of only the finest materials, manufactured to exacting tolerances.