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 extra-light 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 provided and pulling the device downwards. With the DUO and ART bubblers, a small piece of the housing in the cylinder compartment must be cut out so that the cylinder can be inserted into the compartment. 2. Screw the quick adapter with the inserted flat seal hand-tight onto the conventional TR21-4 valve. Fits perfectly on 425g CO2 cylinders, including those from other manufacturers such as Crystal 2.0, Penguin, Cool, and Aqvia. IMPORTANT: If the adapter cannot be screwed onto the CO2 cylinder by hand, the cylinder is not compatible with this adapter. For questions, contact customer support. 3. Insert the 425g cylinder into your Soda DUO, Art, or Terra and secure it by pulling the quick-release device down and pressing it into the sparkling water maker until it clicks into place. IMPORTANT: The TR21-4 valve hex head screw (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 need a reliable connection solution for their Sodastream Terra, Duo, or Art series machines. This quick adapter allows convenient use of compatible CO2 cylinders without modification. Delivery content: 1 x Quick adapter Notes: 1. Due to lighting and screen differences, the item's color may vary slightly from images. 2. Please allow 0.52 cm variation due to manual measurement.