Canon Speedlite Transmitter ST-E2

An integral part of the Canon flash system: on-camera wireless transmitter for Speedlites 420EX, 550EX, 580EX, and Macrolites MR-14EX and MR-24EX. The ST-E2 is a signal transmitter which fits into the camera hot shoe, allowing wireless variable ratio control of up to two groups of compatible Canon Speedlites. Uses a 2CR5 battery (not included)