I have used  the MTN Guide base layer in different temperatures and it is my preferred base layer. Truly fast wicking and dries quickly, it provides me just the warmth I need.  Very good fabric and very nice fit!

I have used this base layer for quite a while now and it is very good. I tend to use this on its own when I am hiking up mountains or climbing, as I run quite hot. The Material handles this very well and the armpit areas really help. The Zip helps to vent excess heat, though it makes it more difficult to hide under a dress shirt for office wear in the winter. The find is quite true to size though I find it a little bit baggy, I am a 34-36" chest and took XS. There is little hem lift while reaching for hand holds while climbing. I will be purchasing this again, partly as other companies do not offer XS mens sizes. Well done Berghaus for this!