Naimo New 3L Hydration Bladder System Water Bag Pouch Backpack Bladder for Outdoor Sports for Cycling Climbing Running It's constructed by waterproof 600D high density oxford fabric material 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 Two layers cargo design,one for hydration bladder,and the other for extra carrying purpose Very light weight at only 14 ounces (0.9 lbs)