IRWIN Tools 1881324 Impact Performance Series Turbomax Black and Gold Drill Bit Pro Set Case, 10-Piece Built for maximum durability and long life with impact drivers.Manufactured with heavy-duty, cold-forged, high-grade steel to withstand high torque output One-piece construction withstands higher torque loads than standard quick-change bits Exclusive TURBOMAX tip eliminates "walking," delivers 10X faster starts, and stays sharp longer Made from premium high speed steel with black oxide finish for added corrosion resistance 10-Piece Pro Set 1/8 (2), 9/64, 5/32, 11/64, 3/16, 7/32, 1/4, 5/16 and 3/8 Inches