it comes with instructions it plugs inline with the injector feed line and runs a chemical cleaning agent through the injectors it will not harm the injectors or engine it is suitable for petrol and deisel injectors and also has a decarbonising cycle the rrp on one of these machines is around 800 to 900 bux however we are having a workshop cleanout and are going in different directions with the work we are doing so the machine is for sale it built by a company called chem tune and i should be able to post pics tomorow