The Relay Shield provides four high-quality relays that can control high current loads to Arduino / Seeeduino boards. It also provides NO (Normally Open) / NC (Normally Closed) interface. It could be a nice solution for controlling devices that could not be directly controlled by Arduino's Digital I/Os. The standardized shield form factor enables a smooth connection with Arduino and compatibles. The shield also has four LED indicators to show the on/off state of each relay.

Relays are useful in switching on/off AC appliances like fan, light, motor or high current DC actuators like solenoid valve, etc…