The middle one (TG-10) came in my FWF package, but I substituted the DL-01SS because it has a flange on the inside. I can put a piece of scat on this and send some heat to my back seater if needed - not needed in an RV-7. I used the middle one on my -6 and like the fact that I didn't have to punch another hole in my firewall for the cable.