Fat Cat Smart Fast Dual Charger + 2 * 1650 mAh AHDBT-302 Batteries Travelling Set for GoPro Hero3+/3. Built-in smart fast charging MCU, over-voltage protection, over-charging protection, short-circuit. Protection circuit. Standard mini +5V power input, dual-charging-slot can are super fast to charge 2 GoPro batteries so that keep enough power and energy for your GoPro camera.