High Quality: The hydration bladders are made of premium PE and EVA material, tasteless, non-toxic, which have passed pressure tolerance tests and greatly improved durability. > Large Capacity: The bladder of the hydration pack can hold up to 2 liters of water at -20 to 50 degrees Celsius. 2 packs (4 liters) can meet all your outdoor activity needs. Leak-proof design: Improved soft mouthpiece with easily accessible on/off valve to prevent leaks. Easily control the water flow by biting, when it does not bite, the water will not leak. The quick release tube is removable. Auto shut-off when tube is removed. Easy to clean and fill: wide opening is big enough to fill water and add ice cubes. The bottle brush can easily access inside and deep clean your water tank bladder. Wide Application: Perfect water bladder for camping, hiking, biking, running, backpacking. cycling, climbing, hiking, hunting and skiing, any other outdoor sport for easy drinking, keeping you hydrated.