Comprehensive set including Chrome Molybdenum screw and bolt extractors and Vanadium stud extractors. Screw-type has left-hand threads for removing recessed bolts/studs. Bolt type features reverse spiral flutes which bite down on rounded off bolts. Stud type includes three internal rollers, clamping down and gripping stud, allowing removal/installation. Suitable for professional workshop. Supplied in storage case.