Complete Auto Changeover LP Gas Regulator Assembly includes: auto changeover regulator, 2 to 24 Inch pigtails, cover and mounting bracket. Red and Green pressure indicator float indicates when cylinder is empty. Large flow indicator knob designates which cylinder is primary. Automatically switches to reserve cylinder when primary empties. Service Technician Tap for performing flow, lockup and leak tests. Pressure adjustable. 1/4 Inch inlet, 3/8 Inch outlet.