This fill adapter set is used to your external large commercial CO2 tanks like 5lb,20lb and 50lb,so that you can refill your DUO,Terra,Art quick disconnect new-version cylinder yourself at home . style:W21.8 / CGA320 Colour:As Shown Material:Metal How to use: 1. Prepare the items you need: wrench, charging connector, large CO2 tank, empty quick-connect bottle. 2. First loosen the exhaust screw, then use the wrench to install our charging connector to your large CO2 tank. 3. Rotate to put the empty bottle into the filling place. 4. Tighten the exhaust valve so that the cylinder is firmly locked. This is the most important step and the feature of our charging valve, so that we can fill the bottle more safely than other CO2 charging connectors. 5. Slowly open the large CO2 tank and refill the CO2 gas into the bottle. After about 15-20 seconds, the cylinder is completely filled. 6. Fill it up completely. Close the large Co2 tank valve first, then unscrew the exhaust valve to release the gas. Remove the bottle-done. Due to different batches, there may be differences in product appearance and printed text, which will not affect use Package Contents: 1 * Co2 Cylinder Refill Fill Station Adaptor 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.