The low-profile shape and durable construction of this 2-liter Hydration Pack will have you thirsting to take longer hikes with fewer water stops. The outer pack is made of rugged and resistant 70D nylon with 5mm closed cell PE insulation. The reservoir uses Glass-LikeTM 3-layer construction that prevents bio-film build up to make the system self-cleaning. Fill the reservoir using either the leakproof Wideslide Widepac opening or easy-opening filler cap. The drinking tube has a pull open valve and Dirt-ShieldTM cover to keep the valve free of dirt. Adjustable shoulder and sternum straps with tough nylon buckles to provide a custom fit.