With the Sierra Designs Cloud 20 Degree 800 DriDown Sleeping Bag, gone are the days of sacrificing comfort for ultralight efficiency. Now you can enjoy cloud-like comfort after long days of trekking, without being burdened with excess weight and bulk on the trail. Its innovative zipperless design features a flap that lets you get in and out easily, but wraps around you when you're lying down in order to seal in precious heat. On warmer nights you can simply push the flap out of the way to vent your core. 800-fill DriDown insulation and 15D fabrics keep weight to a minimum while still packing plenty of warmth, and the down is treated for water-resistance to keep damp nights from leaving you shivering. A half-sleeve on the underside of the bag secures your sleeping pad to create one integrated unit that offers warmth retention and comfort. Another ingenious features it the self-sealing foot vent, which lets you simply raise your knees and poke your toes out when you get stuffy, so you can cool off without messing with any pesky zippers. On the flip side, the adjustable hood easily cinches down to keep your head warm on frigid nights. Considering this bag's innovative design, reasonable price, and frankly incredible levels of warmth and comfort considering its weight, it doesn't seem hyperbolic to call the Cloud 20 a revolutionary achievement.