Battery pack Meike SF-17 is a device designed for additional power supply for Sony HVL-F56AM and HVL-F58AM external flash units. Thanks to its application, you can significantly increase the number of photos that can be taken in one "series". In addition, it allows much faster charging of the lamp capacitors. This is especially useful for all types of journalistic and sports photography. Meike SF-17 is powered by 6 AA batteries. It should be emphasized that the flash itself must also be powered, and the battery pack only provides "recharging". It is recommended to use the same type of cells in both lamps and battery pack. When the device is charging the lamp, the red LED lights up indicating that the capacitors are working. NOTE: there should be no more than 15 flashes in one series. Otherwise, the flash may overheat and damage. After each long series of flashes, allow the lamp time to cool down the torch. The Meike SF-17 battery pack has the option of being attached to the camera body using a tripod thread. Connecting the device is very simple, just place the batteries as shown in the cover, connect the plug to the flash's power input, and then turn on the flash itself. Additional power will be automatically detected by the lamp.