How it works: To use the product correctly, follow these instructions: 1. Cool the soda machine cylinder in the freezer for 1 hour. 2. Attach the CGA320/W21.8 connector to a commercial CO2 gas cylinder. 3. Disconnect the quick connector of the black adapter, then securely tighten the black adapter to the CO2 cylinder. Ensure the knob on top of the black adapter is in the highest position. Do not turn the adapter knob down to open the CO2 cylinder. Pressing the 6mm wide valve pin will close the valve and prevent CO2 from entering. 4. Reconnect the quick connector. 5. For larger cylinders, position the cylinder upside down or horizontally, as some tanks do not contain a dip tube (syphon tube). 6. Carefully open the valve on the large gas cylinder. The valve may restrict flow if opened too wide or too quickly. Open slowly until gas flow is heard. 7. After approximately 15–20 seconds, the cylinder will be fully filled. 8. Close the valve on the large gas cylinder. 9. Open the bleed screw to release any remaining gas. 10. Unscrew and remove the CO2 cartridge. Notes: 1. If liquid CO2 is present, invert the CO2 tank if refilling is not possible while upright, as some tanks lack a dip tube. 2. The cylinder should be empty before use. Pre-cooled cartridges will fill more effectively. 3. Open the tank valve slowly when filling to avoid engaging the 6mm wide safety valve pin on the soda machine bottle. 4. This adapter is not compatible with RPV (residual pressure valve) systems. Refer to the provided image for identification. Some RPV valves can be removed using a hex wrench—verify your tank type before ordering. If your tank has an RPV valve, select the "RPV pushing adapter" option when placing your order.