If you are fitting a diesel heater this part is perfect to connect to your diesel tank WITHOUT the need to remove or drill a hole in your tank! This “clunk clip” tee simply connects to the return pipe and delivers fuel to your diesel heater. It takes just 10 seconds to fit and is by far the easiest way to connect your heater to the tank. You simply disconnect the existing pipe by squeezing the red button and pull the pipe out. Then simply click this tee into the existing pipe and reconnect. No modification to vehicle required. Simply fit in between existing connectors on fuel return line.