1. Nature has a concise appearance with a petal-like texture panel, which express a kind of refreshing and natural. Also, it is with self-clean function. When water-in, Nature will lift the thimble panel up with the buoyancy of water flow automatically. When water stops, the thimble panel falls to the water outlet automatically since gravity, which can squeeze out the dirt at the water outlet. 2. In terms of structural function, Nature realizes the self-cleaning function through the most natural and simplified structural principle, which not only saves materials, labor and other costs, but also safer, more reliable and highly sustainable.