SMAKN&reg; DIY Water Level Switch Sensor Controller /Drainage control circuit board This product is based on the actual use of domestic factories and pumping. The product is based on the detection water level of the pool (water tower) to control high current relay to achieve control pumping. With small, simple wiring, low power, high switching capacity, strong anti-interference function and high stability. Can steady achieve the pool (towers) automatically open the pump when lack of water, automatically stop the pump (solenoid valve) when full of water.