Featuring our warmest-weight merino wool, the heavyweight Women's Core Merino 330 Half-Zip is made to keep you warm in the coldest conditions. Merino wool has an excellent warmth-to-weight ratio to keep you warmer with less bulk and it regulates temperature through stop-and-go activity levels. Merino wool also resists odor to help minimize smell, and our ArmorSpun merino wool is reinforced to last longer than traditional merino wool. And to prevent sweat from leaving you wet and cold, we added a synthetic interior that quickly pulls moisture away from your skin and through your system to keep you dry and warm. Women's Core Merino 330 Half-Zip Optifade Subalpine XL