• Multifunction Hydration Backpack: Constructed from extremely durable, water-resistant 600D polyester and designed to last for years. The convenient headphone jack lets you jam out while keeping your phone dry. Perfect for running, hiking, cycling, camping and day trips. • Designed for Comfort: Lightweight, at 1.22lb, with adjustable shoulder and chest straps for breathable comfort. • Fluorescent Reflectivity: The fluorescent reflective element keeps you safe at night by making you visible from up to 300 foot away. • Insulated Hydration Pack: Insulation keeps your fluids cool even when it's hot outside.