Slide the featherlight Therm-a-Rest Hyperion Sleeping Bag: 20 Degree Down into your trusty backpacking pack before a long through hike. The lightweight and packable construction of this sleeping bag will ensure there is plenty of room in your pack for other necessities. The 900-fill Nikwax Hydrophobic Down makes this warmth and packability possible by trapping your body heat in strategic areas and compressing to an impressively small size. As an added bonus the Nikwax treatment means the down can handle moisture without losing its loft so that a surprise rainstorm wont ruin your trip. This bag also features an ergonomic shape and longer zipper that makes it far more comfortable than some competitors bag in the ultralight category.