What Our Gearhead(R) Experts Are Saying: "The Up First Quarter Zip is warm but breathable, and the underarm panels dump heat when I'm working hard. The zip makes it easy to ventilate, and it layers great under a shell."When movement meets mountain temps, we turn to the Mountain Hardwear Up First Tech Fleece Quarter Zip to manage warmth without overheating. This slim-fitting fleece top blends moisture-wicking stretch fabric with targeted jersey panels under the arms for increased breathability and freedom of movement. It's equally at home on cold-weather trail runs or layered up for alpine missions. The quarter zip design makes for easy on-and-off and provides quick temperature control on the fly. Anti-odor treatment keeps us feeling fresh on extended outings, while thumb loops, a longer back hem, and a secure zip chest pocket make this a cold-season staple for high-output days.