1.Specification:it is an external power source for the Nikon Speedlight. This Battery Pack can hold 8 AA-type batteries, ensuring a stable power supply for the speedlite, greatly increasing the number of flashes, and reducing recycling time.Features:-Protective Case: Protective soft case can be worn on belt or put in a bag; light and easy to carry. The one-way connector plug is designed to avoid mis-connections which can lead to flash unit damage. 1/4" Thread Screw: Standard thread for tripod mount.-Performance: The Pack reduces recycling time to less than half of a normal cycle and can give up to double the amount of flashes as the original (a). It is suitable for continuous flash use (b).-Convenience: The Pack uses 8 AA batteries (same batteries as flash) and with different connecting plugs, supports most Nikon flashes to greatly increase flash capacity. It"s ideal for the professional.Product dimensions: 69mm(w)x158mm(h)x25mm(d) .Net weight: 170g.Operating Temperature range: 0oC-40oC.Suits: Nikon SB900.Package Includes:1 x External Flash Battery Pack (batteries not included),1 x padded protective case, 1 x 1/4 inch screw adaptor & English and Chinese instructions.Note:a, Depending on state of battery charge;b, Maximum of 15 consecutive shots without break or risk of overheating..*Pls kindly note that the item is shipped from China Port.