Perfect Fit: Compatible with DUO/Terra/ Art machines, With this quick adapter, these three devices can connect Cylinders or other Cylinders withTR21-4 Male Thread.of course the adapter can help you connect old hose with TR21-4 Male Thread to Terra/Art/Duo.<br> What you should do:with the quick adapter the bottle will be long to insert,so it is necessary to the base where the 60L CO2 Cylinder stands and then insert the cylinders.if you have Art or Duo maker then please try to remove 4 screws from the base and the bottom, insert the bottle and put the bottom back on.if you have terra maker,then just press the two pink locks then remove the pink base.It only takes a few simple steps to complete.<br> High Quality Material: The co2 adapter is made of high quality brass, anti-corrosion, and safe, with polished , good sealing, high quality, , anti-rust<br> Color: Gold<br> Material: copper+aluminum<br> <br> Package Contents:<br> 1 x Fast adapter<br> <br> Only the above package content, other products are not included.<br> 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.