The Anti-Corrosion Water Level Sensor with Ball Float Switch is a device used to sense the level of liquid within a tank, it may actuate a pump, an indicator, an alarm, or another device. Use them in hydroponics, saltwater tank, freshwater tank, gardening, aquariums for power head control, pet bowls, fish tanks, filtration, heating, or whatever your project may be. The float switch of side mount duckbilled is a frequently opened, often closed, switching contact and with the overall brake, it's installed from the outside and doesn't need to be sealed.