The AC3 ZoneController for Canon is the gem of the ControlTL product line. Add it to your on-camera MiniTT1 Transmitter or FlexTT5 Transceiver and you instantly have three zones of flash control. Whether working in E-TTL II or Manual mode, you now have control over all your flashes directly from the camera's position. Put your flashes wherever you want, without worrying about having to access them during a shoot. With the AC3 ZoneController, you are in total control of your flash.