Using the float principle, the water level controls the inlet and outlet water switch to achieve a constant water level effect, keep enough water and always keep clean water. Always floats in the water, when the water rises, the floats follow the rise. And the rod driven by the rise will also rise. Large water flow, high efficiency, good sealing. Works great for water trough, humidifier, fountain, aquarium, pond, chicken/dog/horse/livestock waterer, etc. Rubber washer ensures waterproof equipment and leak-free, and you can adjust the float arm easily. Item Descriptions: Using float water level principle, the switch controls inlet and outlet water to achieve constant water level effect, keeps sufficient water and always clean water. Floats Silently in Water: When the water rises, the floats follow the rise. And the rod driven by the rise also rises. Large water flow, high efficiency, good sealing. Works great for water trough, humidifier, fountain, aquarium, pond,