The Icebreaker Womens Zone Longsleeve Halfzip Skivvy 2020 midweight baselayer to go over your thermals, featuring 260 gm Merino wool fabric through the body, with a touch of Lycra for stretch. Zoned body mapping panels for warmth and breathability. Flatlock seams prevent chafing. Fully functional for warmth, ventilation, and support while alpine climbing, backcountry skiing, or other day-long adventures.