Source Outdoor Widepac Dvide Hydration System, Transparent Blue Unique hydration reservoir with two flexible compartments and drinking valves -- one for pure water and one for sports drinks Both compartments add up to the full capacity of the bladder for maximum flexibility Easily switch from blue valve for water to the red valve for sports drink when on the trail Taste-free reservoir with maintenance-free Glass Like liner prevents bio-film build-up Rounded Helix bite valves deliver a full flow with just a soft bite; built-in safety shutoff mechanism