[FILLING YOUR CYLINDER]: It only takes a few minutes to fill the cylinder yourself . We provide additional rubber rings, which are made of food-grade materials, safe and reliable, they can a better sealing of the adapter. When old rubber ring aging, you can replace it. Compatible Model: The CO2 adapter only replacement for CGA320 to TR21-4( to CO2 tank with W21.8-14 joint) Easy to Install: The CO2 adapter connector kit is very easy to use, and the adapter is easy to tighten with empty CO2 cylinders.You can install it correctly according to our picture Quality Assurance: High-quality materials have a longer service life and are .Good air tightness, no gas leakage when connected to the cylinder, more convenient to use. Color:Copper Color Material:Copper Package Contents: 2 * Co2 Adapter Refills Connector 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.