Specifications: Material: Aluminum alloy, copper Color: Gold; purple; silver Function: Connects the soda cylinder with TR21-4 thread to the DUO, TERRA, and ART soda machines with quick-connect cylinder Characteristics: Fits many common CO2 cylinders with conventional trapezoidal thread TR21-4, compatible with bottles up to 60 liters and 425 g CO2. Made from robust and lightweight aluminum. Environmentally friendly, sturdy, high security, rustproof, and durable. Instructions: 1. Remove the pink piece from the bottom of the Terra Sparkling Water Maker by pressing in the pins as shown in the instructions and pulling the device downward. For the DUO and ART models, a small section of the housing in the cylinder compartment must be removed to allow proper insertion of the cylinder. 2. Screw the quick adapter with the included flat seal hand-tight onto the conventional TR21-4 valve. Compatible with 425g CO2 cylinders, including those from various brands. IMPORTANT: If the adapter cannot be secured by hand, 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 until it clicks into place. IMPORTANT: The TR21-4 valve hex head (safety valve) must face outward, away from the unit, not sideways or inward. Why choose this adapter? Ideal for users who have a standard CO2 cylinder and need a reliable connection solution for their Sodastream Terra, Duo, or Art series machines. This adapter allows direct use of compatible refillable cylinders without the need for additional tools or modifications. Delivery content: 1 x Quick adapter Note: 1. Due to lighting and screen differences, the actual color may vary slightly from images. 2. Please allow 0.5–2 cm variation due to manual measurement.