Some propane applications need a specific regulated pressure that is impossible to set without a Gauge Kit. The Gas Gauge is typically installed after the gas pipe or gas hose to adjust the regulator to offset the pressure drop experience from the length of the gas line. It is also able to leak check the entire propane system. The Gauge Kit comes in High(5PSI) and Low(15in w.c.) gas pressure ranges and come in 1/2″ and 3/4″ sizes.