i bought under armour coldgear last year and i love the stuff. Not only does it keep you warm, it is so thin that you can additional layers and not feel bulky and most importantly to me it keeps you dry. After you work up a sweat, you are dry within 10-15 minutes, which ultimately keeps you warmer. I will say this, I live in the NE and our season runs late..i found it during our muzzleloader season i used my polartec thermals on days when i was sitting for a long time and when it was really cold.