Item features: Material: Aluminum alloy, Copper Color: Gold; Lilac silver Thread: 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. Made of durable, lightweight aluminum. Environmentally friendly, robust, safe, stainless, and long-lasting. 1. To install, remove the pink piece from the bottom of the Terra water dispenser by pressing the pins as shown in the 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 included flat seal firmly onto the 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. 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 safety valve on the TR21-4 cylinder must face OUTWARD, not sideways or inward toward the machine. Why choose this adapter? Ideal for users who have a blue CO2 cylinder and want to refill it at home. This improved quick adapter allows direct use of compatible CO2 cylinders with TR21-4 threading on Terra, Duo, and Art series soda machines. Scope of delivery: 1 x Quick Adapter