Item features: Material: Aluminum alloy, Copper Color: Gold; Lilac Silver Thread: TR21-4 Function: Connects soda cylinders with TR21-4 thread to DUO and TERRA soda machines with quick-connect cylinder systems Properties: Fits many common CO2 cylinders with standard trapezoidal TR21-4 thread, bottles up to 60 liters and 425g CO2. Made of sturdy and lightweight aluminum. Environmentally friendly, robust, high safety, stainless, and durable. Instructions: 1. Remove the pink piece from the bottom of the Terra Water Sprinkler by pressing the pins as shown in the included instructions and pulling the device downward. For compatibility with DUO and ART bubblers, a small portion of the housing must be removed in the cylinder compartment to allow insertion. 2. Screw the quick adapter with the included flat seal firmly onto the standard TR21-4 valve. Fits perfectly on 425g CO2 cylinders and is also compatible with other brands such as Crystal 2.0, Penguin, Cool, and Aqvia. IMPORTANT: If the adapter cannot be screwed into the CO2 bottle valve, the cylinder is not compatible. 3. Insert the 425g cylinder into your Soda DUO, Art, or Terra machine and secure it by pulling down the quick-release lever and pressing the cylinder into the water dispenser until it clicks into place. IMPORTANT: The hexagonal screw (safety valve) on the TR21-4 valve must face OUTWARD from the device, not sideways or inward. Why choose this adapter? If you have a blue CO2 bottle but cannot refill it easily, or there are no refill stations nearby, this improved quick adapter allows you to use pink CO2 bottles with compatible sparkling water machines. Simply refill your blue bottle, attach the adapter, and use it with Terra, Duo, or Art series Sodastream machines. Package includes: 1 x Quick Adapter