Dujiangyan water conservancy project has a long history, large scale, reasonable layout, scientific operation, harmonious combination with the environment, and outstanding historical and scientific popularization value, so Dujiangyan has been identified as a world cultural heritage.
The bottle mouth plays the role of "inspection door" and can automatically control the inflow of Neijiang. It was dug up from Kanshan Mountain (now called Guankou Mountain and Leiyu Mountain) on the long ridge of Minjiang River. It was artificially cut to control the inflow of Neijiang. Because it looks like a bottle mouth and has peculiar functions, it is named Bao bottle mouth.
Li Dui was a part of Hutou Rock in Xushan before digging the bottle mouth. Because of its magnificent natural landscape, the bottle mouth is known as "Staying Piles to Lock the Gorge" and is one of the famous "Ten Scenes of Guanyang" in history.