Controls three independent groups of lights from your camera position Works in E-TTL or manual mode Allows for 1/3 f-stop increments of power control Adjusts the relative light level of each zone independantly E-TTL II Compatibility: Using PocketWizards ControlTL system, the AC3 is designed to work seamlessly with Canons E-TTL II system. Three Zone Control: Control up to three zones of light, each with one or more flashes, right from the cameras position. Wide range of control: With three simple dials, you can quickly adjust the power settings for three independent zones in clearly labeled 1/3 stop increments over a six stop range. Studio Flash Compatibility A FlexTT5 paired with an AC9 AlienBees Adapter, and White Lightning studio flash. Coming with AC9