Compatibility: Fits standard CO2 cylinders with TR21-4 trapezoidal thread. Compatible with water aerators DUO, Art, and Terra. High-quality material: Made of brass, rust-resistant, abrasion-resistant, and high-strength. Ensures safety, durability, and long service life. Easy to install: One end connects to the Duo water carbonator; the other connects to a 60-liter CO2 cylinder with TR21-4 thread. To install, remove the pink part from the bottom of the soda machine (press the pin to pull). For newer DUO and ART models, a small portion of the bottle compartment housing may need to be trimmed to accommodate the cylinder. Efficient and economical: Enables continued use of original CO2 cylinders, reducing replacement effort and cost. Also supports CO2 cylinders from previous versions. Important note: Before purchasing, confirm that your CO2 cylinder—including its valve—is original (not Quooker-branded), as the adapter may not fully engage with non-original valves in newer soda machines. Color: Red Material: Metal Package contents: 1 x CO2 Quick Adapter 1 x Sealing ring Note: Color appearance may vary slightly due to lighting and screen settings. Measurement tolerance: ±1–3 cm.