Warm pants mainly for breaks. I've used it once while moving, last Christmas when I went for a leisurely day walk it was -25 and when I came back a couple of hours later it was -27. Just merino pants underneath, but my groin is still sweaty. Christmas overeating could also play a role. The sizing has taken into account that these can be worn over everything else. They still stay on thanks to the belt. Quality ones. They don't pack into as small a space as down-filled ones, but they are more affordable and probably more durable, the filling doesn't come out of the small spark hole. For the winter hiker traveling with Ahkio.