For the past couple of weeks I’ve been trying out some new under layers. I’ve been rocking Burton base layers for years now and they have been both warm and stood up to the conditions well. I have to say though that I found and even warmer base layer that are also comfy too. The Coldpruf extreme performance Tops and Bottoms have a 2 layer system for warmth. Made of mostly CPT Performance Polyester. The moisture management fiber wicks & evaporates moisture and controls odor. I’m impressed with these base layers and they are much cheaper than buying a named brand like Burton. I used to wear 3 Burton base layers under my jacket and body armor, now with the Coldpruf addition I only need 2 layers underneath the jacket to maintain the same body temps in the extreme cold. I got the tops/bottoms from www.outersports.com