Feature:1. The thread size is W21.8-14 // TR21-4, the refill adapter can be used to refill a small CO2 cylinder from a larger CO2 cylinder.2. It has good sealing performance, no air leakage when connected with the cylinder, and it is more convenient to use.3. Exquisite workmanship, excellent performance, stable performance, is a very practical accessory.4. The installation method is simple and practical, and the old or damaged parts can be replaced directly.5. Integrated safety valve, strong and durable in use, you can use it for a long time.Specification:Item Type: CO2 Refill AdapterMaterial: Aluminium AlloyColor: BlackInterface Diameter: 21.8mm/0.86inWeight: Approx.96g/3.4ozThread Interface: W21.8-14 // TR21-4Applicable Countries: South Korea, Japan, Britain, Germany, France, Poland, Norway, Switzerland, Russia, Ukraine, South Africa, Sweden, Chile, Czech Republic, Singapore... (some countries are also called DIN477 /JIS m22-14)The refill adapter can be used to replenish a small carbon dioxide tank from a larger carbon dioxide tank. The refill adapter is W21.8-14. Make sure that the thread type of the carbon dioxide tank is the same..Package List:1 x CO2 Refill AdapterNote:1. Please allow 1‑2mm error due to manual measurement. Thanks for your understanding.2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.3. Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.