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 various manufacturers. IMPORTANT: If you cannot screw the adapter into the CO2 cylinder valve, this cylinder is not compatible with this adapter. For any questions, support is available. 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 standard CO2 cylinders but want compatibility with sparkling water machines that use quick-connect systems. If you have a blue CO2 cylinder and no nearby refill station, this adapter allows you to refill and use it with your Terra, Duo, or Art series soda machine. Scope of delivery: 1 x Quick Adapter