I've used 3 packs that have claims to air flow , they being Deuter Air Contact, Osprey Kestrel, and a Granite Gear Blaze AC 60. All performed well, but still made my back sweat. For myself, the only thing that keeps my back comfortable is what I wear. Generally ,shirts that wick and dry moisture rapidly. In my experience, the reduced contact directly on your back helps, but does not completely eliminate the problem.