Material: Aluminum alloy, Copper. Color: as shown. Function: Connect CO2 cylinders with TR21-4 thread to Sodastream Duo, Art, Terra machines with quick connection. Properties: Fits many common CO2 cylinders with conventional trapezoidal thread TR21-4, bottles up to 60 litre and 425g CO2. Made of sturdy and extra light aluminium, environmentally friendly, robust, high safety, stainless and durable. Installation Steps: 1. Remove the pink piece from the bottom of the Terra Water Sprinkler by pressing the pins as shown in the supplied instructions and pulling the device out downwards. For DUO and ART bubblers, a small piece of the housing must be cut out in the cylinder compartment so that the cylinder can be inserted into the compartment. 2. Screw the quick adapter with the inserted flat seal firmly onto the conventional TR21-4 valve. Fits perfectly on 425g CO2 cylinders and cylinders of other manufacturers such as Crystal 2.0, Penguin, Cool and Aqvia. IMPORTANT: If the adapter cannot be screwed into the CO2 bottle HANDLE, this cylinder is not compatible. 3. Insert the 425g cylinder into your Soda DUO, Art or Terra and fix it as usual by pulling down the quick release device and pressing into the water spreader until the device clicks into place. IMPORTANT: The hexagonal screw (safety valve) of the TR21-4 valve must be positioned so that it looks OUT of the device and NOT sideways or into the storage device. Scope of delivery: 1*Quick Adapter