Can be used to sense the level of liquid in a tank, easy to use. A 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 other device. Use them with hydroponics, saltwater tank, freshwater tank, gardening, aquariums for power head control, pet bowls, fish tanks, filtration, heating etc. This liquid float switch can be installed as a normally closed/normally open switch according to your needs. Switching voltage (Max): 0-220V DC; Switching current (Max): 1.5A. --------------0