Improve the recycle time of your Speedlite with the CP-E4N Compact Battery Pack from Canon, which can hold 8 AA batteries. This pack gives your flash a boost for faster continuous shooting and with improved heat management can allow for more bursts before needing to stop. This capability works well with the larger battery capacity to increase the number of flashes before needing to recharge. Additionally, it comes with a carrying case so you can easily have it attached to a strap or belt loop.
Speedlite 600EX RT
Speedlite 580EX II