I went there, but do not understand what the mechanisim is that prevents ice from building up on the outter layer fabric.<br><br>it seems to me that no matter what the outter fabric is that any moisture will freeze on contact. Even if the insulation does not collect water vapor, the vapor will condense when it hit the layer of fabric that is outter most. if the bag is inside a canvass cover the canvass will freeze, if the bad has no cover the out fabric will freeze.....<br><br>it seems to me that you would still need a vapor barrier at below 0'.<br><br>When a bag freezes it does so from the out side and works in from that point. it takes a few days to get started with that process, but the insulation left frozen seals the bag with ice, and then the ice builds up to a point that if not dried the bag becomes useless.<br><br>I would like your report if at all possible, or your take if you have not yet had time to try this bag and idea out.......<br>i simply don't understand...... mac