Pocket/Pitzip inside out
Heres a large M10 inside out. The pitzip is underneath the mesh if you look closely(in green). The 2-way pitzip itself is 17-1/2". You basically have a huge pocket on each side. You can have the pitzip open and still carry things in the pockets .... just don't open the pitzip all the way to the bottom, you'll still get plenty of ventilation.
The photo uploader appears broken, I tried both Firefox and Chrome.... ho-hum ..