Uniweld RHP500 is a durable brass piston designed diaphragm Nitrogen Regulator with a Delivery Pressure 0-500 PSI for purging and pressure testing air conditioning and refrigeration systems. Regulator with CGA580 inlet connection, 1/4 inch male flare outlet connection, self re-seating relief valve (not designed to protect downstream system) and easy to read 2 inch Contents Gauge 0-4000 PSI (Part No. G7SD) and Delivery Gauge 0-600 PSI (Part No. G8SD) with protective rubber gauge boots (Part No. GB20S). For smooth accurate delivery pressure adjustment there is a large brass Tee Handle with stainless steel pressure adjusting screw and regulator bushing that prevents galling. Regulator can be used with CO2 with the Uniweld part no. F36 adaptor, CO2 Cylinder (CGA320) to Nitrogen Regulator (CGA580) (purchased separately).