Our LIFA® Merino Midweight collection is perfect for any type of activity in cold weather. We combined a 100% Merino wool layer with our proven LIFA® Stay Warm tech in a 2-layer construction on this ½ zip. LIFA® Merino Midweight Base Layer delivers all the breathable warmth of Merino wool fibers, plus the unique moisture management properties of LIFA® fibers.