1. TD-382 is a power pack for Nikon flashgun . 2. TD-382 uses a dual circuit charging system. Charging time is much fast than any other battery pack. 3. Convenient design; you can either use 4 or 8 AA batteries. It will be faster recharged when using 8 AA batteries. 4. TD-382 uses a new trigger method, its almost no power consumption under the stand-by mode. 5. Compatible flash: Nikon SB-900