Thanks to its ProlightTX fabric, the Mammut Sphere UL 5 Degree Down Winter Sleeping Bag is exceptionally light, compressible, and more importantly, warm. One of the lightest bags in Mammut's line of bomber sleeping bags, this winter bag will keep you warm when you're exploring cold and high environments, without adding a bunch of excess weight to your backpack. The bag's outer fabric is treated with a DWR finish for water resistance. The hood of the bag is designed to provide a full field of vision even when it is completely cinched down. Wave shaped baffles prevent down migration and eliminate cold spots from developing throughout the night. The ergonomically designed foot box gives your feet some wiggle room while you sleep and enhances the overall warmth of the foot area.