icebreaker’s Men's 200 Zone Knit Long Sleeve Zip Neck uses Zone Knit body mapping technology to actively regulate body temperature for high-intensity winter sports. This multi-purpose base layer is made with 100% Merino wool, which is breathable, naturally odour-resistant, & soft against the skin. It features a half zip for venting. The slim fit, flatlock seams, & low-profile thumb loops ensure it layers comfortably without bunching or chafing. Plus, gusseted underarms ensure full mobility.