Opteka External Flash Battery Pack for Canon 580EX, 580EX II, 550EX, 540EZ, MR-14EX, MT-24EX Speedlite Flash Units External power source for higher flash capacity Reduces recycle time by 60-75% Powered by 6 AA batteries (not included) Includes padded carry case Dimensions: 6.88CM X 15.79CM X 2.48CM (W X H X D) Weight: 170g (without batteries)