This tool cleans up the fuel injector cups, when replaceing fuelinjectors or seals. This tool is for all diesel engines. The injector seals get burned on to the cups and this tool cleans off the burnt seal material. Allso over time the seals can make deep grooves in to the cups ware the seals sit. This tool can reserface the cups smooth again, so the new seals can seal again .The tool gets put into a drill and is spun slowly, with diesel fuel ,WD-40 or any light oil. This tool works on all diesel engines ; Cat ,Commins, International, duramax , detroit ,percins, ford etc. The cost $ 25.00 dollars.