Product Features: Material: Aluminum Alloy, Copper Color: Gold; Purple; Silver Subject: TR21-4 Function: Connects a soda cylinder with TR21-4 thread to DUO, TERRA soda makers with quick-connect cylinders. Features: Fits many common CO2 cylinders with the conventional trapezoidal thread TR21-4, bottles up to 60 liters and 425g CO2. Made of robust and extra-lightweight aluminum. Environmentally friendly, robust, high safety, rust-free, and durable. 1. Remove the pink piece from the bottom of the Terra Water Sprinkler by pressing the pins as shown in the included instructions and pulling the unit downwards. For DUO and ART bubblers, a small piece of the housing needs to be cut out in the cylinder compartment so that the cylinder can be inserted into the compartment. 2. Screw our quick adapter with the inserted flat seal firmly onto the conventional TR21-4 valve. Fits perfectly on our 425g CO2 cylinders but of course also on other manufacturers' cylinders such as 2.0, Penguin, Cool, and Aqvia. IMPORTANT: If the adapter cannot be screwed into the CO2 bottle's HANDLE, this cylinder is not compatible with this adapter. If you have any questions, we are happy to answer them. 3. Insert the 425g cylinder into your Soda DUO, Art, or Terra and fix it as usual by pulling down the quick-connect device and pressing into the water sprinkler until the unit clicks into place. IMPORTANT: The hexagon screw (safety valve) on the TR21-4 valve must be positioned so that it faces OUT of the unit and NOT sideways or into the storage unit. Why Choose Us? What if you only have a blue CO2 bottle but are too lazy to go out and refill it? Or are there no gas stations nearby? The improved quick adapter from WADEO, specially developed for sparkling water makers with pink CO2 bottles. If you only have the blue CO2 bottle, take this adapter home, you can refill the blue bottle directly, then add the adapter, then you can use it on Terra/Duo/Art series Sodastream soda makers. Delivery Scope: 1*Quick Adapter