Featuring polished surface. good sealing and anti-oxidation. the quick-adapter is anti-corrosion. durable and safe. In just a few simple steps. your CO2 soda maker can be used with this quick adapter. With this quick adapter. these soda devices can connect old cylinders or other cylinders with TR21-4 Male Thread. Of course. the adapter can help you connect old soda hose with TR21-4 Male Thread to Terra/Art/Duo. It is made of high-quality copper and aluminum material. The length of the product is 3.5cm. and the height is 3.5cm. The caliber is 2cm. Compatible with Soda DUO/Terra/ Art machines. Item Name: Quick CO2 Adapter Material: Copper. Aluminum Features: Easy Installation. Good Sealing. Anti-oxidation Size Details: LxH: 3.5cm x 3.5cm/1.38" x 1.38" (Approx.) Caliber: 2cm/0.79" (Approx.) Notes: Due to the light and screen setting difference. the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Adapter 2 x Sealing Rings