A heavyweight merino wool base layer top for highly aerobic days in cold weather, the warm and odor-resistant 260 Zone Long Sleeve Half Zip features zoned ventilation panels for active temperature regulation and ample breathability. The Zone’s body-mapping technology combines a merino wool and LYCRA blend with strategically zoned panels of eyelet merino mesh that actively controls temperature. The classic half-zip design makes for easy layering and quick temperature regulation while the gusseted construction increases range of motion. Flatlock seams make for a soft next-to-skin feel. Inspired by nature, icebreaker harnesses the performance qualities of natural fibers to offer an alternative to clothing based on petrochemical synthetics. Merino is an annually renewable fiber that naturally resists odors, keeps you cool when it’s hot and warm when it’s not, and lets your skin breathe for comfort all day, every day.