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 with quick-connect cylinder system Properties: Fits common CO2 cylinders with standard trapezoidal TR21-4 thread, compatible with bottles up to 60 liters and 425g CO2 content. 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 device 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 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. 3. Insert the 425g cylinder into your Soda DUO, Art, or Terra machine and secure it by pulling down 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, not sideways or inward toward the housing. Why choose this adapter? Ideal for users who have a blue CO2 cylinder and need a convenient way to refill. This improved quick adapter is designed for compatibility with popular sparkling water makers and allows use of refillable cylinders. Package includes: 1 x Quick Adapter