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, bottles with up to 60 liters and 425 g CO2. Made from robust and extra-light aluminum. Environmentally friendly, sturdy, high security, rustproof and durable. 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, as well as on cylinders 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. 3. Insert the 425 g cylinder into your Soda DUO, Art or Terra and fix it as usual by pulling the quick-release device down and pressing it into the sparkling water maker until it snaps into place. IMPORTANT: The TR21-4 valve hex head screw (safety valve) must face outward from the unit, not sideways or inward toward the soda machine. Why choose this adapter? This improved quick adapter is designed for sparkling water makers that use CO2 cylinders with TR21-4 threading. If you have a standard 425g CO2 cylinder, this adapter allows you to connect it directly to Sodastream Terra, Duo, or Art series soda machines after refilling. Delivery content: 1 x Quick adapter Note: 1. Due to lighting and screen differences, the item's color may vary slightly from the images. 2. Please allow 0.5–2 cm differences due to manual measurement.