Take only what is necessary for radio wireless remote flash and camera control out of the Canon Speedlite 600EX-RT Flash , and what you have left is the Canon Speedlite Transmitter ST-E3-RT.

This transmitter is great. The menu is easy to understand, the build quality is good. I only have one flash so far but its great to have it off the camera. Im looking forward to controlling multiple flashes from my camera in the near future.

I was hoping to use this instead of the flimsy, unreliable cable connection when using a flash bracket. I also was hoping to use it to aid in fill flash for some outdoor sports, taking advantage of the long range so the flash unit could be located closer to the action.

This is a hit or miss item! By that I mean sometimes it works perfectly sometimes it doesn't work at all. Every assignment is a crap shoot. It works great then it doesn't work at all even with the camera an inch from the flash!

Quality build

Doesn't work ever shot

I was surprised how easy it was to establish great connection between my camera and my flash. It was also so easy to do that with my three flashes at the same time. Either easy connection all on one group, or group each one on it's own group from A to C.

Works well with your off camera speedlites. It can be a pain to reach a speedlite on a stand with an umbrella or other lite modifier, but with the transmitter changing your light settings is a breeze.

Durable; Easy To Use; Lightweight; Reliable

Gives out of sight control, with all the same menus as on the flash. Simple to use either in full TTL or manual mode.

Easy Setup; Lightweight

This is a FANTASTIC tool if you own a Canon wireless Radio Transmitter Flash like the 600EX-RT and wish to shoot remotely or with multiple Flash units. Don't be put off by the minor price differences between the ST-E3-RT Transmitter and those slightly cheaper 3rd-Party 2.4ghz Transmitters: When you...

I was using an extra flash to fire the other flashes but this is way better. Lighter on the camera and everything is available form the ST.