The Mammut Taiss Neck Gaiter uses Polartec Power Stretch fleece with 4-way stretch, wicking sweat away during a hard climb and holding warmth once the pace slows on the descent. The recycled polyester blend keeps the fabric durable through repeated wear without adding bulk under a helmet or hood. We reach for this on ski tours and winter hikes alike, since it manages moisture as well as it blocks cold. What Our Gearhead(R) Experts Are Saying:"I pushed hard on a skin track climb and never felt this gaiter trap sweat against my neck. It stayed just as warm once I dropped into the descent, without needing to pull it down to cool off."