When active in Arctic-like conditions, optimal performance hinges on your base layer's proper/ability to control of the relative humidity and temperature closest to your body, without restricting movement. Made with Polartec Power Stretch, the Sphere Pullover will flex as you flex, and keep you dry when you sweat. The soft inner face wicks moisture away from your skin. The moisture is then transported to the fabric's outer face, where the increased surface area enables it to dry out twice as fast as cotton. Next-to-skin fit, construction, and comfort features, like a velour-lined collar and abrasion-free flat lock seams. Wraps your body core and arms with a snug, unrestrictive fit. Other than the increased performance and dry comfort provided, you won't even notice the Sphere Pullover is there, just the way it ought to be.