Material: Aluminum Alloy, Copper Color: Gold; Lilac Silver Theme: TR21-4 Function: Connects soda cylinders with TR21-4 thread to DUO, TERRA soda machines with quick connect cylinder Fits many common CO2 cylinders with traditional trapezoidal thread TR21-4, bottle capacity up to 60 liters, CO2 capacity 425 grams. Made of strong and ultra-light aluminum. Environmentally friendly, high safety, stainless steel, and durable. 1. Press the pins as indicated in the included instructions, pull the device down and remove the pink part from the bottom of the Terra sprinkler. Compatible with DUO and ART bubblers. A small piece of the housing must be cut out in the cylinder compartment to insert the cylinder into the compartment. 2. Screw the quick adapter with the inserted flat seal securely onto the conventional TR21-4 valve. Perfect fit for 425g CO2 cylinders, including those from other manufacturers such as Crystal 2.0, Penguin, Cool, and Aqvia. 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 and secure it as usual by pulling down the quick release and pressing in the water diffuser until the unit clicks into place. IMPORTANT: The hexagon screw (safety valve) of the TR21-4 valve must be placed outside the device, not on the side or inside the storage unit. Why choose this adapter? Designed for users who have a blue CO2 cylinder but need compatibility with pink CO2 bottle systems. This improved quick adapter allows direct use of compatible blue CO2 cylinders with Terra, Duo, or Art series Sodastream machines after installation. Scope of delivery: 1 x Quick Adapter