The Odin TCU TTL Flash Trigger for Canon from is a wireless transmitter that runs on the 2. 4 GHz frequency, has 4 channels with 3 groups and can fire your Canon flash from a distance of 328' with separate purchase of a receiver. Flashes within each group have +/- 3 EV power compensation in TTL or user-determined power levels in manual mode. The transmitter can also remotely adjust the angle of the flash beam via its zoom button. The Odin is compatible with Strato 4-in1 and Strato II Multi 5-in-1 wireless systems. Items Include: Odin TCU Transmitter 2AA Batteries USB Cable Instructions CD