Nylon .Imported .PERFECT FIT: Package size 16.5 x 8 x 6.0 inches with adjustable shoulder chest & waist straps will fit teens/ with 27 inches chest size and adults (men and women) with 50 inches chest size. Chest and waist straps ensure the bag doesn't bounce around when you move. .LIGHTWEIGHT & SPLASH RESISTANT & DURABLE: & Splash Resistant nylon is upgraded with 2 Liter balder (total 1.1lb) to reduce your load and protect your belongings, & Splash Resistant stays dry in light rain, and dual built-in waist straps increase wear and tear resistance to ensure the bag's lifespan longer. .REPLACEABLE 2L BLADDER: Contains a 2 Liter/ 70z BPA bladder to keep you hydrated. The airflow system also keeps the water extremely cool. Includes a screw cap to add small ice cubes for a day of hiking, biking, running or riding. SMALL FRONT POCKET: Designed specifically for RACING with a SMALL FRONT PACK, a bunch of keys and a granola or two. LIGHTWEIGHT & COMPACT PERFORMANCE: Designed with cyclists, runners and hikers in mind, the hydration pack is compact and aerodynamic, ing a feather-light balance on your back and minimizing wind resistance. They deliver top-notch performance that's perfect for intense activities from marathon training to cycling adventures.