Please check your tank thread before ordering. OD: 22mm W21.8-14 / DIN477 / M22-14 for your large CO2 tank. Common in Russia, Korea, Japan, UK, France, Switzerland, Sweden, Ukraine, Germany, South Africa, Czech Republic, Singapore, etc. This item is used to refill small CO2 tanks from large tanks, allowing easy refilling of small tanks. CO2 Refilling Station Charging Adapter Type: W21.8-14 How it works: To use correctly, follow these instructions: 1. Cool the cylinder in the freezer for 1 hour. 2. Screw the CGA320/W21.8 connection to a commercial CO2 gas cylinder. 3. Disconnect the quick connector of the black adapter, then tighten the black adapter to the cylinder (must turn the knob on the top of the black adapter to the highest position; do not turn the adapter knob down to open the cylinder. If the adjusting rod is pressed down 6mm, it closes the valve and CO2 cannot enter). 4. Connect the quick connector. 5. For most large cylinders: turn the large cylinder upside down or lay it down (some host tanks do not have a dip/syphon tube inside). 6. Carefully open the valve of the large gas bottle (the valve on the cylinder closes the flow if opened too much. This happens if the large cylinder is opened too quickly. Open the large cylinder slowly. You will hear the airflow. This ensures successful filling). 7. After about 15–20 seconds, the cylinder is completely filled. 8. Close the valve of the large gas bottle. 9. Open the bleed screw to release residual gas. 10. Unscrew the CO2 – done. Color: Black Material: Metal Package Contents: 1 x Charging Valve Connector Only the above package content is included; other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture to vary slightly.