It is extremely unpleasant when the bolt to be unscrewed is broken off during disassembly so that a piece of it remains screwed inside. At such times, there is no way to do without extractors. The essence of their action is simple: the extractor cuts alternative slits in the broken stud or self-tapping screw. Then the bit is repositioned with the reverse side, which works only for unscrewing and will cling to the cut slots. The set comes with 4 different sized extractors that are used to extract bolts from 3mm to 12mm. The extractors are suitable for drill and screwdriver.