The PowerPack 7800 Portable Power Charger from PNY Technologies comes with dual USB ports for charging. The PowerPack also has a built-in digital screen to show you how much juice remains in the battery.
The PowerPack itself charges using a standard Micro USB cable, so you can use your normal phone charger to power it up. The PowerPack 7800 is made of lightweight brushed aluminum and is compact enough to fit in your bag.
20" (50.8 cm) Micro USB Cable
PNY Technologies PowerPack 7800 Portable Power Charger