I looked at these long and hard. I purchased some Rocky boots with 600 grams of thinsulate ultra, and considered these to compliment them. I am a freak of nature, with a 3E foot width, and "normal" width boots constrict my blood flow, leading to cold feet no matter what I do. I bought the Rockys in their widest width, which I believe is 2E, and they are much more comfortable, although I still can't wear thick socks, only poly liner socks. I wanted to see if 600 grams of thinsulate would be enough before I bought the articshield covers, and while I didn't get cold feet from constriction, yesterday told me 600 grams while not moving sitting in a treestand in below 30* temps isn't enough. I plan to by some articshields before next season, and like the fact that they are not bulky and can easily be carried in my daypack...