I haven't used this for polar expedition, but have loved it on very cold days even for routine use.
This jacket is too warm for me if I'm active and it's above 0 deg. F.
Size large is generous. I wear 46 regular and this fits with room to spare.
I've used it below -30 F. with moderate activity (hiking with pack) and it's a bit warm. For hanging around camp before bed it's most awesome. It
This review was written in the old system and had content requirements that are different than reviews written today.