The DFRobot Relay Module blocks the number of electronic modules. It can be used in interactive projects. It can also be used to control the lighting, electrical and other equipments. The modular design makes it easy to expand with the Arduino board (not included). The Relay output state by a light-emitting diode. It can be controlled through the digital IO port, such as solenoid valves, lamps, motors and other high current or high voltage devices.