This AutoMeter High Pressure Fuel Isolator is required when running a fuel injected engine with a mechanical fuel pressure gauge mounted in the vehicle interior. This isolator assembly mounts between the gauge and the fuel pressure port on your regulator or fuel rail and translates fuel pressure readings to the gauge keeping flammable materials out of the passenger compartment. This brass bodied version from AutoMeter is safe for competition use and includes -4AN fittings 4 ft. of PTFE lined braided stainless hose fill kit hardware. and instructions for proper setup.