USPRO 4 channel 5V relay shield expansion board V1.3 Arduino dedicated Relay shields,supporting 4 channel 3A relay control,xbee wireless module and so on. Independent external power supply and opto-isolator. Power apply:7V-12V(&gt;200mA) Contact load capacity:1A 250VAC , 3A 120VA/24VDC Wireless output interface:xbee/Bluetooth Bee/Wireless Programming Module