Perma-Coil helically coiled inserts are made of stainless steel wire that has been rolled to a carefully controlled thread form. When installed, Perma-Coil inserts adjust to a tapped hole, becoming a functional thread with a strength exceeding the original. Perma-Coil inserts and repair kits are designed to repair stripped threads in a variety of metals. Aluminum, aluminum alloys, steel, and cast iron. If the original threads can be stripped, Perma-Coil inserts can repair them. By following the detailed instructions provided with every kit, even an inexperienced do-it-yourselfer can repair stripped threads, permanently. Repair Kit contains 12 inserts, installation tool and tap.