jameswest421868wrote a review of Craft Active Extreme Concept Base Layer - Long-Sleeve - Men's on March 3, 2013
Bought for xc skiing. When climbing a long hill, you sweat, a lot, this design allows the heat to dissipate while keeping your arms warm and chest. I just cannot say enough about how much I love it and I'm very picky on design, fit, etc. used today on 25 km classic ski with 1000' gain.