Item features: Material: Aluminum alloy, Copper Color: Gold; Lilac silver Thread type: TR21-4 Function: Connects CO2 cylinders with TR21-4 thread to DUO, TERRA, and ART soda machines using quick connection system Properties: Fits common CO2 cylinders with standard trapezoidal TR21-4 thread, compatible with bottles up to 60 liters and 425g CO2. Made of durable, lightweight aluminum. Environmentally friendly, robust, safe, stainless, and long-lasting. Instructions: 1. Remove the pink piece from the bottom of the Terra water dispenser by pressing the pins as shown in the included instructions and pulling the unit downward. For compatibility with DUO and ART models, a small section of the housing in the cylinder compartment may need to be removed to allow proper insertion of the cylinder. 2. Screw the quick adapter, with the flat seal inserted, firmly onto the standard TR21-4 valve. Compatible with 425g CO2 cylinders, including those from various brands. IMPORTANT: If the adapter cannot be screwed into the CO2 cylinder valve, the cylinder is not compatible with this adapter. Contact customer support for assistance. 3. Insert the 425g cylinder into your Soda DUO, Art, or Terra machine and secure it by lowering the quick-release lever and pressing the cylinder into place until it clicks. IMPORTANT: The hexagonal screw (safety valve) on the TR21-4 valve must face OUTWARD from the device, not sideways or inward toward the housing. Why choose this product? Ideal solution when you have a CO2 cylinder but need a convenient way to connect it to your sparkling water maker. This upgraded quick adapter is designed for use with compatible soda machines, allowing easy connection of CO2 cylinders with TR21-4 threading. Package includes: 1 x Quick Adapter