Function: 1. SUITABLE MODELS: Male connector CO2 cartridge CO2 adapter is suitable for DUO, for TERRA, for Art soda makers. 2. THREAD AND USE: The thread of our CO2 adapter is TR21 4 male thread which can be inserted after removing the base of the 60L CO2 cylinder, there are different methods of use depending on different cylinders, easy to install. 3. POLISHED SURFACE AND GOOD SEALING: CO2 cartridge CO2 adapter has a well-polished surface and good sealing so that CO2 does not leak. 4. EASY TO CARRY: The total weight of this CO2 connector for soda maker is light and very easy to carry, you can take the connector with you all the time. 5. MADE OF BRASS AND ALUMINUM ALLOY: Carbonated beverage cartridge CO2 adapter is made of brass and aluminum alloy, corrosion resistant, durable and safe. Specification: Item Type: CO2 Adapter Material: Brass, Aluminum Alloy Thread: TR21 4 Thread Function: Connects TR21 4 threaded CO2 cylinders to DUO, TERRA, Art soda makers that use gas cylinders. With this adapter, you can continue to use traditional screw-valve CO2 cylinders. The adapter can be used with 60L aluminum CO2 cylinders with screw valves. Package List: 1 x Connector 2 x Washer Note: When connecting the TR21 4 threaded CO2 cylinder with the connector, if it is found that the gas cylinder cannot be inserted into the machine, it is necessary to remove the baffle at the bottom of the machine, so that the connector and the gas cylinder can be inserted into the machine together.