Six Lobed Spiral Bits are Designed to Remove Rounded or Stripped Fasteners with Internal Drive Heads. Ten sizes of extractors fit Torx and Torx Plus sizes T-10 to T-55; internal hex sizes 7/64" to 3/8" and 3mm to 10mm. Will also work on other internal drive screw heads. To remove broken bolts, drill a pilot hole for the appropriate size extractor. Choose the extractor that fits snugly in the fastener. Turn counter-clockwise to remove fastener. It may be necessary in some applications to drive the extractor into the fastener with a hammer for maximum torque.