Helly Hansen Warm Freeze 1/2 Zip Mens Long Underwear Top 57% Merino wool, 43% Polypropylene Imported Non itch, 1/2 zip opening 1/2 Zip turtle designed for cold weather activities Lifa thermic tube technology (T3) mimics the performance of polar bear fur Hollow core Lifa fibers insulate the body and wick away moisture Super fine merino wool outer layer is extremely warm and itch free 1/2 Zip neckline, flat lock stitching, and low bulk cuffs