Feature:1.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.2.Use them with hydroponics, saltwater tank, freshwater tank, gardening, aquariums for power head control, pet bowls, fish tanks, filtration, heating etc.Working theory:One or more reed tubes are mounted in a closed, non-permeable tube.Then the tube is passed through one or more of the hollow and internally floating magnets.The rise or fall of the liquid level causes the floating ball to move together, thereby causing the reed switch in the non-permeable tube to be actuated to open or close and output a switching signal.Specification:Material: plasticContract rating (Max): 10WSwitching voltage (Max): 100V DCSwitching current (Max): 0.5ABreakdown voltage (Max): 220V DCCarry current (Max): 1AContract resistance (Max): 100O OHMTemperature rating: -30 ~ +125 Celsius degreePacking list:1 x Water Level SwitchNote:Float used in conjunction with the relay can not be directly used with the power supply.