The Relay is the most common used module in actually application such as home automation, and sometimes you need to control large current such as the air conditioning/water heater. That is what this Large Current Relay Module can be help. 
This Large Current Relay Module is a high quality Single Pole Souble Throw Relay(SPST). When the relay not triggered, the 2 outputs is disconnected; when the relay triggered(Logic Low), the 2 outputs connected, the max current can be up to 30A@240VAC or 30A@30VDC, which would be enough for most of the home appliances.