The CO2 cylinder refill adapter comes with a 3500psi/2000psi pressure gauge that can monitor pressure changes in real time. Please select the appropriate pressure gauge . When using it, please that the pressure value does not exceed the pressure specification of the receiving tank. First, loosen the vent screw, then use a wrench to install the fill fitting onto the (CGA320) Large CO2 Tank, then rotate the empty cylinder to the fill position and tighten the vent valve to lock the cylinder securely in place. Finally, slowly open the large CO2 tank to fill. Refill Co2 only fits Soda Terra Duo or Art Soda Maker CO2 cylinder which is pink color. Our adapter does not work RPV valve (residual pressure valve), but some RPV valves can be removed by hex key, please check before ordering. The refill adapter is made of aluminum alloy and stainless steel, which is corrosion-resistant, oxidation-resistant and long-lasting, etc. It can withstand the pressure well, and you can inflate CO2 at any time