Lofty goals are reachable, with the right layers. Our SmartLoft is made of a hybrid construction, giving you the ultimate in breathability as you climb your mountain. The arms are constructed with Stretch HyFi fabric – wind – resistant and water repellant nylon on the outside with soft Merino on the inside. Lofted wool insulated for breathability and warmth without the bulk covers the torso. This hybrid construction layers perfectly with our Merino 250 base layer, giving you the ability to heat up, without having to ditch a layer.