The Unique Extractor Kit is designed to make screw and bolt extraction faster, easier and safer. Lefthanded cobalt drill bits create a pilot hole for the extractor and also loosen, or even remove, corroded threaded fasteners. The straight-fluted extractors provide extra bite in the pilot hole and can be torqued in either direction to loosen a frozen screw or bolt. For use with screw or bolt diameters of ¼ to 5/8-inches, this 10-piece kit contains five straight-fluted, alloy steel extractors and five matched lefthanded cobalt drill bits.