Perma-Coil Spark Plug Kits is a quick and easy way to repair worn or stripped spark plug threads. Spark Plug kits are available in 10, 12, 14, and 18mm sizes. Each kit includes the appropriate reamer/tap and installation tool for all sizes. For the 12 & 14mm, you choose the reach and quantity of Perma-Coil stainless steel inserts required. It's not recommended to use Perma-Coil wire spark plug inserts to repair taper seat spark plug ports. 12mm and 14mm spark plug kits contain tap and installation tool ONLY - NO inserts in kit. Purchase packages of inserts separately. Same tools are applicable regardless of insert reach.