The PocketWizard TTL 4-Pack is the ideal solution to compliment your existing FlexTT5 or MiniTT1, to expand your lighting control.Consisting of 2 x FlexTT5 Transceivers; an AC3 ZoneController; and a G-Wiz Uber bag. The FlexTT5 transceivers can be attached to off-camera flashes or lights, to allow them to be controlled by the MiniTT1 Transmitter (or additional FlexTT5). Add the AC3 ZoneController to the on-camera FlexTT5/MiniTT1 transceiver to create up to three zones of flash control in both TTL and Manual mode. The PocketWizard TTL 4-Pack is the perfect answer for on-location or studio wireless TTL shooting. PocketWizard TTL 4-Pack – Canon: Key Features Dedicated TTL Triggering Manual Power Control HyperSync High Speed Sync (Auto FP) USB Upgradeable Made for Canon 52 channels; 3 zones 340-354 MHz