The Performance Tool W86910 Spark Plug Repair Kit is designed for M14-1.25 thread size spark plugs. It includes a tapered reamer that eliminates the need for a drill bit and restores threads to their original size. The kit comes with (1) 4241 HSS Tapered reamer, (3) 503 Stainless steel inserts in lengths of 5/16 in., 7/16 in., and 5/8 in., and (1) Install/punch tool, providing comprehensive solutions for spark plug repairs.