Sutton Tools Fix-A-Thred thread inserts restore damaged internal threads back to original size. This high quality thread system protects against failure due to stripping, seizing, corrosion, temperature and wear. Ideal for automotive, truck, motorcycle, marine, garden equipment, machinery and more. How It Works: The insert is slightly larger than the tapped hole. During installation, the coil insert undergoes a diameter reduction, which places outward force to permanently lock it into place. The spring-like design of the insert spreads the load over the entire bolt and hole, reducing stud fracture and increasing holding or pull-out strength. This results in a far stronger thread than can be obtained by using conventional drilling or tapping.