BMOUO DC12V External Power Bank Charger Charging Cable Adapter for Microsoft Surface Pro 3 12.2 inch Tabelt Compatible with Microsoft Surface Pro 3 Only!! (Not Fit for Surface RT/ Pro/ Pro2!!) PLS NOTE: Requires 12V 2.5A external power bank / mobile power supply!!! It is portable for you to connect to 12V 2.5A external power bank. Suitable for DC plug size: 5.5*2.5mm or 5.5*2.1mm High speed charge, Tinned Copper, Electromagnetic Immunity