Nylon .Imported .PERFECT FIT: Sized at 16.5 x 8 x 6.0 inches, this hydration pack features adjustable shoulder, chest, and waist straps. It comfortably fits teens with a 27-inch chest and adults (men and women) with up to a 50-inch chest. The chest and waist straps ensure stability and prevent bouncing during movement. .LIGHTWEIGHT, SPLASH RESISTANT, AND DURABLE: Made from upgraded splash-resistant nylon, this pack weighs only 1.1 lbs when filled with the included 2-liter bladder. It protects your belongings from light rain while dual built-in waist straps enhance durability for long-lasting use. .REPLACEABLE 2L BLADDER: The hydration system includes a 2-liter (70 oz) BPA-free bladder that keeps water cool. The airflow system ensures refreshing hydration, and the screw cap allows for adding ice cubes, making it ideal for hiking, biking, running, or riding. .SMALL FRONT POCKET: The small front pocket is designed for racing essentials, providing convenient storage for keys and snacks like granola bars. .LIGHTWEIGHT & COMPACT PERFORMANCE: Tailored for cyclists, runners, and hikers, this hydration pack is aerodynamic and compact. It balances lightly on your back, minimizing wind resistance. Perfect for intense activities such as marathon training or cycling adventures, delivering reliable performance throughout your journey.