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 and pulling the device downward. For the DUO and ART bubblers, a small section of the housing in the cylinder compartment must be removed to allow insertion of the cylinder. 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 on hand-tight, the cylinder is not compatible. 3. Insert the 425g cylinder into your Soda DUO, Art, or Terra and secure it by pulling the quick-release lever down and pressing it into place until it clicks. IMPORTANT: The TR21-4 valve hex head screw (safety valve) must face outward, not sideways or inward toward the machine. Why choose this adapter? Ideal for users who have a standard CO2 cylinder and need a reliable connection solution for their sparkling water maker. This improved quick adapter is designed for use with soda machines requiring TR21-4 threaded cylinders, enabling convenient use with compatible refillable cylinders. 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 0.52 cm differences due to manual measurement.