The Women's Patagonia Nano-Air Ultralight Pullover features shell and lining fabric made from 100% recycled polyester ripstop with mechanical stretch, exceptional breathability, and improved abrasion resistance. Light, breathable, and stretchy 20-g FullRange insulation provides featherlight warmth through the shoulders, outer arms, and front and back body, while uninsulated underarm panels vent heat and reduce bulk. The slim fit is designed for comfort under a harness and backpack, with articulated patterning that allows an exceptional range of motion. A deep, two-way center-front zipper offers venting and includes a smooth, low-profile zipper garage for next-to-skin comfort. A low-profile, generously sized, vertically zippered chest pocket keeps essentials warm and close at hand, and the pullover easily self-stuffs into it with a carabiner clip-in loop. Stretchy, soft, moisture-wicking, and quick-drying Capilene Cool Lightweight fabric at the lower arms adds extra stretch for pushing sleeves up the forearms.