The Zion is a great three season bag when light weight and small volume are important. Perfect for the backcountry, thru-hikers, or anyone wanting to spend some time in the great outdoors. Thanks to the superior weight to insulation ratio of the 850+ fill power premium goose down this bag packs a big punch into a small package. Like our other models, the dimensions of our standard cut mummy bags provide you with sleep system ergonomics that achieve the perfect balance of comfort and weight. A locking #5 YKK zipper, coupled with a full down draft tube and draft collar, seal out the cold.