Material: Aluminum alloy, Copper Color: Gold; Lilac Silver Topic: TR21-4 Function: Connects CO2 cylinders with TR21-4 thread to DUO, TERRA, and ART soda machines with quick connection system Features: 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 alloy. Environmentally friendly, robust, safe, stainless, and long-lasting. Compatibility Instructions: 1. For use with Terra Water Sprinkler, remove the pink piece from the bottom by pressing the pins as shown in the instructions and pulling the device downward. For compatibility with DUO and ART bubblers, a small portion of the housing in the cylinder compartment may need to be trimmed 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 does not screw 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 pulling down the quick-release lever and pressing until it clicks into place. Important: The hexagonal safety valve (screw) on the TR21-4 must face outward, not sideways or inward toward the device. 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 refilled blue cylinders with Terra, Duo, and Art series Sodastream machines. Package Includes: 1 x Quick Adapter