When using, be sure to pay attention to the following points: 1. the sealing device is in the correct position. Therefore, upon receipt of the soda bottle filling connector, make sure that the correct seal is used on the correct side. 2. Make sure to place the soda bottle on the correct side. The large CO2 bottle can only be mounted on the rounded side. Therefore, you must place the soda bottle into the hexagonal one measure. Please note:the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! How to use: 1. Screw the adapter onto a commercial CO2 cylinder. 2. Screw the empty soda cylinder into the adapter. 3. Open the valve of the large gas cylinder 4. After about 15-20 seconds, the cylinder is completely filled. 5. Close the valve of the large gas cylinder 6. Open the venting screw to discharge the remaining gas 7. Check the inflatable connector - done! Specification:B:TR21-4 to CGA320(outlet valve diameter 21mm) Colour:As Shown Material:brass Package Contents: 1 * for Refill Adapter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.