ST-E3-R3 Wireless Controller
For 600EX Speedlite
For professionals who demand ultimate control of their lights, the ST-E3 delivers. Capable of remotely triggering up to 15 600EX flashes in five groups at a range of 30 meters, this controller mirrors the controls on the 600EX Speedlite, making complex lighting setups a breeze. Because it uses a radio signal, you no longer have to depend on having a clear line of sight between your camera and your lights, which means your lights will go off reliably, no matter what gets in the way.