Universal 7/16"-14 Perma-Coil Repair Kit (1208-107) by Thread Kits. Perma-Coil helically coiled inserts are made from 304 (18-8) stainless steel that has been rolled to a carefully controlled diamond shape thread form. Designed to be slightly oversized in diameter, when installed into a STI (Screw Thread Insert) tapped hole, the insert expands outward with a spring-like action that securely grips the wall of the parent material providing a much stronger, permanent thread. Perma-Coil inserts and repair kits are designed to repair stripped threads in a variety of metals including aluminum, aluminum alloys, magnesium, cast iron and bronze. If the original threads can be stripped, there is a Perma-Coil insert to repair it.