Perma-Coil kits are designed to repair stripped spark plug port threads to like new or better than original condition. By following the detailed instructions enclosed in every kit, even an inexperienced mechanic can repair stripped threads, permanently. Perma-Coil inserts meet all applicable industrial and military specifications. They may be used on all military and government airplanes and other vehicles covered by MS21208, MS21209, and NAS1222. Kit includes Tap, Installation Tool, and 6 18MMx.5” inserts. Additional inserts are available: see p/n 418-500. 2 lbs (1Kg) shipping weight.