We think this is pretty much the perfect baselayer. For the Enigma, OR blended their proprietary driRelease recycled polyester with 12% wool to create a plush fabric that is ultra comfortable against the skin for all-day outings. And it's just enough wool to keep you warm but not overheated during high exertion. This top quickly wicks sweat, dries in a flash, and inhibits odor. The flat seem construction eliminates chafing points, and the sleeve feature thumb loops to make layering super easy.