Can be used to detect the liquid level in a tank, easy to use. A float switch is a device used to detect the liquid level in a tank, it can operate a pump, indicator, alarm, or other device. Use them with hydroponics, saltwater aquariums, freshwater tanks, gardening, aquariums to control the power head, 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. Features: simple structure, long service life, easy to use The float switch is a device used to detect the liquid level in the tank. It can activate pumps, indicators, alarms or other devices. Use them with hydroponics, seawater tanks, freshwater tanks, gardening, aquariums for electric head control, pet bowls, aquariums, filtration, heating, etc. working principle: One or more reed tubes are installed in a closed non-permeable tube, and then the tube is passed through one or more hollow, floating magnets. The rise or fall of the liquid level causes the floating ball to move, so that the reed switch in the impermeable pipe operates, opens or closes, and emits a switch signal. Switching voltage (max): 100V DC ; Switching current (max): 0.5A Delivery quantity: 3 pieces