The Irwin Bolt-Grip Bolt Extractor Base Set contains 5 of the most commonly used bolt extractor sizes to easily remove rounded off, rusted-over or painted-on bolts. Bolt-Grip bolt extractors feature reverse spiral flutes that bite down on the bolt to ensure maximum gripping power to break free bolts in almost any condition. Constructed of high carbon steel, they are designed for increased durability and extended tool life. The universal lobular design works with all fastener types and the 3/8 in. square drive can be used with impact wrenches and hand and air ratchets. The bolt extractor kit also contains hexagonal flats to use with flat wrenches, pliers, adjustable wrenches, sockets or Vise-Grip locking pliers.