A proven and effective repair system for damaged spark plug threads (e.g. in light metal cylinder heads). A time- and cost-saving solution. because the repair can be carried out without dismantling the cylinder head. Thanks to a special thread drill, old thread residues are removed and a new thread is cut in one step. The threaded parts are securely and gas-tight. do not unscrew when replacing the spark plug later. The threaded parts made of special steel are thin and corrosion-resistant (internal thread M14x1.25/external thread M16x1.25).