Phottix External Hot-Shoe Flash Battery Pack for Nikon gives your flash the power of 8 AA batteries for faster recharges. Hook a huge amount of power to compatible Nikon and Canon hot shoe flashes. For event or wedding photographers this is a must-have item. Super-fast flash recharging – never miss a shot. Compatible Flashes Canon:600EX-RT, 580EXII, 580EX, 550EX, MR-14EX, MT-24EX Nikon:SB-900, SB-910 Technical Specs Power: 8x AA type battery (Not included) Dimensions: 72. 5(W) x 170(H) x 24(D) mm Weight (without batteries): 200g Battery Type - Alkaline-Manganese Number of Flashes (Approx. ): 250 Times Recycle Time (Approx. ): 0. 2-5 sec. Battery Type - Ni-MH Rechargeable Number of Flashes (Approx. ): 500 Times Recycle Time (Approx. ): 0. 2-4 sec. Battery Type - Lithium Number of Flashes (Approx. ): 700 Times Recycle Time (Approx. ): 0. 2-7 sec. Items Include: 1 - Phottix Flash External Battery Pack 1 - Mounting screw 1 - Bag 1 - manual