The package includes a spare GoPro standard battery, plus the plug-in BacPac, replacement waterproof door, replacement skeleton door and USB charging cable.

This clever device doubles your battery capacity when attached to the Hero2 camera. But even more useful is its ability to operate as a stand-alone battery charger when the camera is in use.

So by plugging it into your computer or USB in-car charger, one battery can always be on charge while the other camera is powering the camera, Then just swap batteries when the camera one runs out.

Brilliant!