The Lisle Corp. 4-pc Stripped Screw Extractor Set, No. 62110, includes six lobed spiral bits which are designed to remove rounded or stripped fasteners with internal drive heads. Four sizes of extractors fit Torx and Torx Plus sizes T-40 to T-55; internal hex sizes 1/4" to 1/2" and 6mm to 13mm. This set will also work on other stripped or rounded internal drive screw heads. Made of heat-treated alloy steel for durability.