IRWIN Tools Power-Grip Screw and Bolt Extractor Set, 7-Piece (394100) This screw extractor set has a 1/4-inch hex shank that fits most drills and quick-change adapters High-carbon steel construction gives each bolt extractor longer life and increased durability This set of bolt extractors includes a convenient plastic case These screw extractors have reverse spiral flutes that bite down to provide a high amount of gripping power Universal lobular design fits virtually all types of fasteners Designed for use with power tools 1/4-Inch hex shank fits most power tools When you are faced with a rounded-off, rusted-tight or painted-over bolt, bolt extractors will break it free Reverse spiral flutes are designed to bite down to provide Maximum gripping power High carbon steel ensures longer life and greater durability