Specifications: Material: aluminum alloy, copper Color: gold; purple; silver Function: Connects the soda cylinder with TR21-4 thread to the DUO, TERRA soda machine 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 may need to be removed to allow proper insertion of the cylinder. 2. Screw the quick adapter with the included flat seal hand-tight onto the standard TR21-4 valve. Compatible with 425g CO2 cylinders, including those from various brands. IMPORTANT: If the adapter cannot be securely attached by hand, the cylinder is not compatible. Contact customer support for assistance. 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 product? Ideal for users who have a standard CO2 cylinder and want convenient compatibility with Sodastream Terra, Duo, or Art series machines. This adapter allows easy connection of compatible cylinders, helping extend use between refills. 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 size variation due to manual measurement.