Here's how it works: 1. Chill the Soda Stream cylinder in the freezer for 1 hour. 2. Adjust the pin valve tool to a suitable position. (If you choose not to use the pin valve tool, you can skip this step.) 3. Screw the adapter onto a commercial CO2 gas cylinder 4. Screw the empty CO2 cylinder into the adapter 5. For most large cylinders: turn the large cylinder upside down. (If you can't refill when the CO2 tank is standing, it's because some tanks don't have a dip/siphon tube inside.) 6. Gently open the valve on the large gas bottle. The valve on the Soda Stream cylinder will shut off the flow if opened too much. This happens if you open the large cylinder too much/too quickly. The trick is to open the large cylinder very gently. You will hear the airflow. So to fill it successfully 7. After about 15-20 seconds, the cylinder is completely filled 8. Close the valve on the large gas bottle 9. Open the bleed screw to vent any remaining gas 10. Unscrew the CO2 cartridge - done! When shopping, please pay attention to the size and dimensions of the product to ensure that it meets your needs. In the title and description, we have provided detailed information about the product, including its features and specifications. We want you to be completely satisfied with your purchase, so if you have any questions or concerns, please do not hesitate to contact us. We are here to help and will do our best to assist you. Thank you for choosing our product. We hope you enjoy it.