When using the Arduino do interactive projects, a lot of heavy current or high voltage equipment is usually not directly use the Arduino digital IO port control(such as solenoid valves, lights, motors, etc.), can consider to use solutions of relay.
Arduino Relay shields is to use pine le Relay with high quality, provide 4 road input and output, the highest can meet 250 v / 10A communication device Or dc 24 v /10A equipment, thus can be used to control lights, motors, etc.
Modular design makes it easy to plate is connected with the Arduino extension. Relay output state is represented by a light emitting diode, convenient and practical use.