LAAGIE &trade; 12v 2.5a Dc Connector Portable Charging Cable for Microsoft Surface Pro3 12 Inch Tablet Pc Portable Charging Charger Cable for Microsoft Surface Pro 3 12 Inch Tablet (Pro 3 Charging Cable) Charging cable fits for Microsoft Surface Pro 3 12 Inch Tablet high speed charge, Tinned copper, Electromagnetic Immunity short circuit protection, over-voltage protection. Interface: 5.5mm(outer diameter)*2.1mm(inter diameter) NOTE: ONLY for 12V 2.5A mobile power supply!!! No USB port!