9VDC 1A Arduino Compatible Power Supply Adapter 110V AC 5.5 x 2.1mm Tip Positive Part#LJH -186

2-flat-pin plug | 110V input voltage / 9VDC 1A output voltage | For use with Arduino Uno, Mega and MB102 Power supply boards | Connector size: 5.5 x 2.1mm with Center Tip positive, sleeve is negative | These adapters do not work for guitar pedals or label makers which require negative tip power adapters