This plastic carbonation cap has been designed to suit soda bottes, coke bottles, and FermZilla lids. If you have a keg system you should have at least a couple of these as they are so useful.

NOTE: The duotight fitting shown in the photos does not come included.  If you want to attach the duotight fitting on the back of this fitting then you can use the this one that will allow you to attach 8mm OD EVABarrier 4mm or 5mm ID Beer Line.  If you want to use the large 6mm ID x 9.5mm OD EVAbarrier line you can use this duotight fitting.