The Irwin Tools 1840316 19-Piece Impact Series Drill/Drive Set is part of the new line of Fastener Drive bits designed for use in impact drivers. While most screw driving bits are simply compatible with impact drills and drivers, Irwin's Impact Performance Series fastener drive bits are engineered for maximum durability and long life with impact drivers. These bits are forged rather than milled, so they fit fasteners more precisely which reduces stripping and increases the life of the bit itself. Irwin's Impact Series bits have three times longer life than traditional bits. Manufactured with heavy duty, cold forged, high grade steel, they'll withstand extremely high torque output. Plus, a black oxide finish resists corrosion and increases the life of the bit. The 19-Piece set comes in an Impact Series Pro Set Case for organization and protection. This set contains 6 Black Ox twist drill bits with 1/4-Inch Hex Shank (1/16-Inch, 3/32-Inch, 1/8-Inch, 5/32-Inch, 3/16-Inch, and 1/4-Inch). The 19 piece set also has 7 insert bits including all three Phillips sizes and all 3 Square Recess sizes along with a Magnetic Insert Bit holder, a 3-1/16-Inch Magnetic Screw guide and 3 Magnetic Lobular Nut Setters.