A float sensor or a float switch is a sensor used to detect the level of liquid (water) in a tank. Normally the purpose of a float switch is to open or close a circuit as the level of a liquid rises or falls.
Our float sensor has a magnet on the float (the moving part) and a reed switch on the stem (fixed part). So when the magnet comes near the reed switch the reed switch is activated and the circuit becomes closed.
You can test our float sensor using multi meter. Set the multi meter in continuity mode and then move the float so when the float comes near the reed switch the a tone (beep) is emitted from the multi meter.