On my Colorado archery elk hunt this year we spent a lot of time hunting water holes and, coming from the southeast, my body was not used to the cold in early Sept and I nearly froze to death a couple mornings. I vowed that I would not let this happen again and did a good bit of research here and it was very helpful. I bought pieces by Sitka, Kuiu and First Lite. And with deer season here at home I have had a chance to use some of the clothing and it has all performed well. But the First Lite Furnace has really impressed me more than any other single piece of hunting clothing I own. I still can not understand how something so comparatively lightweight can be so warm. I wear it as a mid layer and it has eliminated the need for wearing heavier, much more bulky clothing. A medium weight fleece pullover used next to skin with the Furnace over it and then a light jacket will allow me to sit in a tree stand in the 20's. After New Year's we switch from deer to ducks and I know the Furnace will be perfect for cold days standing in freezing water.