econoLED US Army 3L 3 Liter (100 ounce) Hydration Pack Bladder Water Bag Pouch Hiking Climbing Survival Outdoor Backpack US EconoLed 3L TPU Hydration System Bladder Water Bag Constructed by waterproof 600D high density Nylon material. Two layers cargo design, one for hydration bladder, and the other for extra carrying purpose. Adjustable shoulder strap and chest belt, suitable for heavy carrying. Equipped with a tube with a bite valve to drink, so you don't need to hold it to drink. A switch on/off bite valve, convenient for control the flow of water.