The Mammut Eiger Free ML Air Half Zip Hoodie uses Polartec Alpha Direct insulation to trap heat while letting excess moisture escape on a hard ascent, so we stay warm without overheating. A long half-zip front opens fast when the pace picks up and closes just as quickly once we stop climbing, letting this hoodie work as a midlayer under a shell or stand alone on a high-output mission. A fitted, helmet-compatible hood layers cleanly under a ski or climbing helmet. What Our Gearhead(R) Experts Are Saying:"I skinned a full ascent with the zip open the whole way and never overheated, then zipped it shut at the ridge and stayed warm while the wind picked up. It's the rare layer that works exactly as hard as I do."