The Canon ST-E3-RT Speedlite transmitter makes sophisticated remote flash photography easy. Fire up to 15 flashes at once and control settings from a distance, even when your sight is blocked by a corner. You can fire up to 15 cameras at once from up to 30 meters for complex, synchronized shooting. The transmitter is sealed against dust and moisture to the same degree as a professional EOS camera, meaning you can be outside without fear of damage. Finally, a backlit LCD control screen is easy to read and use.