"Tips: After the water bag is full, please tighten the lid. The backpack fits the water bag alone. When the water bag is full of water, the backpack only leaves a small amount of space for other items. When using, pressing from the back will speed up the filling of the water bag. Do not fill the water bag completely. Do not put the water bag together with sharp objects (such as keys).Hands-free: If the water bag has problems during the first test, please send us a message for help. Pictures are better and we will solve your problem quickly. The drinking tube comes with a bite valve, gently bite the valve to turn on the water flow.Easy to use: There is a pocket on the back of the water bag, you can easily carry your mobile phone, keys and some small tools. Unisex backpack; sports cut, fully adjustable, suitable for all frames; comfortable tape shoulder straps with mesh cover, means you can carry this backpack for hoursMultiple UsesHands-free drinking tube with bite valve, gently bite the valve to turn on the water flow. A great companion for running, hiking, cycling and other outdoor sports. Fully removable 3-liter water bag. A backpack for men, women and kids to stay hydratedDurable and Reusable: The backpack is made of waterproof 600D nylon material, which is easy to carry and durable."