Uxcell Straight Rod Water Level Sensor Float Switch, 32 cm Long, DC100V, 0.5 Amp, 10W
A retroreflective arrangement places the transmitter and receiver at the same location and uses a reflector to bounce the light beam back from the transmitter to the receiver. An object is sensed when the beam is interrupted and fails to reach the receiver. Can be applied in security system, manufacturing industry.