Yeeco 30A High Current 12V Contactor relay Switch Power Switch DC power Switching Control Board Control Module electrical relay switches for Cooler Heater Refit Water Heater Control Input: 12V DC (relay powered) Control voltage: 250V Max 30A High Current 12V Contactor relay Switch DC power Switching Control Board 30A single channel relay of 4 terminal shunt(Two Input and Two Output) It can be used to cooler control ,heater control ,refit water heater control