One is a large backpack with a volume between 50 and 80 liters, and the other is a small backpack between 20 and 35 liters, also known as a "surprise package". Hill mainly used for mountaineering in the transport of mountaineering materials, small mountaineering bags are generally used for high-altitude climbing or surprise peak. Mountaineering dedicated backpack is to cope with extreme environment, the production of elegant and unique, the general package is elongated, the back of the package of human natural curve design, so that the body close to the back of the person to reduce the straps on the shoulders of pressure. This kind of bag is waterproof treatment, even in the heavy rain will not leak. In addition, mountaineering packages are also widely used in other expeditions (such as rafting, crossing deserts, etc.) and long-distance travel, in addition to mountaineering.