The Napsack has zippers at the shoulders, so you can stick your arms out, and a cinch at the bottom so that you can open it up and stick your legs out. The chest pocket fits a phone and has a pass through hole for your headphones to run internally, and it has pockets like a puffy jacket. Hike it up to your waist, cinch it, and wear it like a puffy coat. Perfect for summer trips, couch surfing, music festivals, jumping into after snowboarding, or any other activity that brings your core temperature down. sizing: s- Fits up to 5'0". M- Fits up to 5'8". L- Fits up to 6'3". XL- Fits up to 6'8"