For use on some Taper Seat spark plug repairs that have very limited access to the hole. Note: Extended version you would need the extended tap found in the extended versions of our spark plug repair kit p/n 4412E to use the tool. Tool will only cut the taper seat counterbore. Be aware the reduced step/stop on this tool is very small so do not use too much down pressure. The reduced step/stop approximately found 2mm from front of tool.