Hew DIN477 W21.8 Tank CO2 Refill Adapter Connector Kit for Filling CGA320 Tank #3 product manual: This Deluxe kit allow to safely refill CGA320 tank from larger donor tank. . It consists of two parts ,can be removed. ON/OFF valve for safe and controlled release of gas. It has a Escape Valve to safely release the residual gas within the adapter once refilling is completed. With a pressure gauge to ensure the pressure will not exceed the pressure specification of the recipient tank. This part has been precision machined from solid brass, polished, surface plating. Very strong and beautiful appearance. Easy installation. CGA320 tank thread: .825"-14 NGO large tank Connect thread: DIN477 / W21.8-14 / JIS m22-14 Valve of CO2 Tank (KOR, JP, UK, Germany, France, Poland, Norway, Switzerland, Rus.