FeaturesConnectors: 5.5x2.1mm male Barrel Jack, USB Plug Male CableMaximum Outside Diameter of Wire :3.5mm/0.14Inches.Nominal Cross Section :0.3 mm square. Descriptions:Use a power adapter with a barrel connector to power and charge USB devices. This is a great way to create a higher current USB charger using the extra barrel chargers that you have lying around.
eBay