Specifications: Material: aluminum alloy, copper Color: gold; purple; silver Function: Connect the soda cylinder with TR21-4 thread to the DUO, TERRA soda machine with quick connect cylinder Characteristics: Fits many common CO2 cylinders which have the conventional trapezoidal thread TR21-4, bottles with up to 60 liters and 425 g CO2. Made from robust and extra-light aluminium. 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 our quick adapter with the inserted flat seal hand-tight onto the conventional TR21-4 valve. Fits perfectly on our 425g CO2 cylinders but of course also on cylinders from other manufacturers such as the Crystal 2.0, Penguin, Cool and Aqvia. IMPORTANT: If the adapter CANNOT be screwed onto the CO2 cylinder HAND-TIGHT, this cylinder is not compale with this adapter. If you have any questions, we will be happy to answer them. 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 the device snaps into place. IMPORTANT: The TR21-4 valve hex head screw (safety valve) must be positioned so that it faces OUT of the unit and NOT sideways or into the soda machine. Why choose us? What if you only have one blue CO2 cylinder but are too lazy to go out and refill it? Or are there no gas stations nearby? This improved quick adapter specially designed for sparkling water makers with pink CO2 bottles. If you only have the blue CO2 bottle, take this adapter home, you can refill the blue bottle directly, then add the adapter, then you can use it on Sodastream Terra/Duo/Art series soda machines. Delivery content: 1*Quick adapter A notice: 1.Due to the light and screen difference, the item& 39;s color may be slightly different from the pictures. 2.Please allow 0.5-2cm differences due to manual measurement."