These are great if you use them correctly. This winter in Alaska it got down to -40 where I live and these thermals were worn daily. I work indoors, but still have to experience many drafts at home or at work. The drive to and from work also exposes me to the harsh temps. I wear these under my clothes all day and I don't sweat in them when indoors at 60 yet they provide an extra layer when I pass in and out of the frigid cold. If I plan to be outdoors standing around or playing hockey I dress differently. I would feel comfortable outdoors in these as another layer down to probably about 10 or 15 degrees. They are great though you just have to use them for the right situation.