The Mobile Mummy 600 Sleeping Bag from Sierra Designs has all the features you want out of a dedicated backpacking bag. The 600 fill duck DriDown combines the best of down, its warmth to weight ratio, with synthetic fill's ability to stay dry and still insulate when wet. A draft collar, tube and draft side curtains help to seal out the elements and preserve your body's natural heat, a must for efficiency in the backcountry. The centrally placed, two way zipper is easy to maneuver with either hand and can be zipped up from the bottom in order to gain some ventilation on warmer nights. Zipperless arm ports at the side allow you to wake up in the morning and make coffee, all without leaving the comfort of your sleeping bag and tent. The footbox at the bottom can be opened, letting your feet get out to breathe and cool down. Not only that, but it can be stowed up behind the bag, letting you walk around camp without dragging the bottom of the bag on the ground.