When you have a gap, it's time to build a bridge.
Welcome to the ReVolt Bridge Cable. One end is battery-shaped and goes into the battery compartment of the device you want to power, while the other end has a power connector. The two are connected by a thin ribbon cable, robust enough to deliver power to your device, yet flat enough to allow you to easily close the door on the device's battery compartment.
With ReVolt, you'll never need to put batteries in there again. Now you can power it whichever way suits you - from a wall phone charger, a USB port on your laptop, a USB powerbank, a USB wall plug, or even from a USB solar cell.