Canon ST-E2 Speedlite Transmitter

The Canon ST-E2 IR Speedlite Transmitter is a dedicated E-TTL (II) wireless autoflash transmitter that can control an unlimited number of flashes with Canon Speedlites 420EX, 430EX, 430EXII, 550EX, 580EX and 580EX in two separate groups; A and B.