GoPro's Battery BacPac is a great dual-function device for improving the functionality of your 1080p HD HERO camera. Able to charge your spare batteries via a USB power source, it also works as a second power supply to give you nearly twice the amount of recording time. With the included backdoors the unit fits into the HD HERO or wrist housing, making it ideal for the kinds of extended shoots required for endurance motorsports and time-lapse photography.