This new EVA Double walled tubing is made with an EVA outter wall and also an inner proprietary polymer barrier.
 
Outter Barrier
The outter barrier has accurately extruded tolerances and made from an EVA material. It also seals well when used with various John Guest, DuoTight or other push in fittings.  The outter barrier gives the tubing excellent kink resistance so the line is able to bend around a tight radius without kinking.
 
Inner Barrier
The inner barrier is made from a proprietary polymer that has excellent gas barrier.  The significantly better barrier properties means your beer is better protected from oxygen and also has a better barrier to CO2 loss.  So your beer will stay fresher for longer and not loose carbonation like other beer line types.  In some beer line types you may notice that the beer sitting in the lines starts to taste flat and/or oxidised when sitting in the lines for an extended period. 
 
EVABarrier tubing is signficaintly better in this regard and you will notice a significantly improved freshness of your beer especially if it's been sitting in the lines.
 
Due to the high denisty and smooth nature of the EVABarrier inner barrier the tubing internal surface is super smooth and almost completely impermiable.  This makes it difficult for bacteria and other microbes to attach to the inside surface of the tubing.