I purchased a Warmbag this winter for treestand hunting and can say it is well worth the money. I use to layer up and after shooting a deer, I would track it only to be sweating by the time I got to deer. Then field dress it and drag back to my truck I would burn up and be miserable. On my way to treestand I would get hot and sweaty only to start freezing a couple of hours later. Now with the Warmbag I dress lightly and stay dry and warm all day. I was hunting the other week in 19 degree weather with 5-10 mph winds and was not affected at all while the others in my group met up early cause they were freezing.