Review on Nalgene Bottle Carrier Insulated: Keep Your 32 Oz Bottles Cold in Gray by Tom Reasons

This insulating sleeve is designed for cold and frosty weather. So I can't understand why they squeaked at the zipper. In cold weather, the zipper becomes brittle and breaks. It is also difficult to open the case when it contains sand, snow or ice getting into the zipper. Also, I found that I had to add another layer - a wool sock - or the sleeve wouldn't insulate properly. An inner monolayer material that reflects thermal radiation can be useful for conditions like the vacuum of space, but is generally less useful here on Earth, where much of the heat is lost through conduction and convection.