This AC/DC Power Adapter design with a flat US plug to 5.5mmx2.1mm Male plug and long cable. It works at AC100V to AC240V 50/60HZ and output DC 9V/2A with a 5.5x2.1mm center-positive barrel jack. It works great for any device with the DC 9V/2A power supply. Such as the Arduino board and so on.