As most professional photographers, the Yongnuo RF603's was probably the first transmitter they used to get their flash off camera, and yes it was my first transmitter too! Lets jump straight into it! Its a great transmitter, its solid, it has a metal hot shoe, its reliable and does what it is supposed to. It even has the basic 1-2-3-4 channel switch, which you can customise giving you more than enough channels to play on. You can also connect more than 1 flash up, often we fired 3 flashes on the same channel with no issues. The battery life on these guys is also pretty good. They take 2 x AAA's per transmitter. If you use the cable supplied you can also use a transmitter as a wireless trigger for your camera, the button on the Yongnuo even has the half way focus point so you can grab focus wirelessly before you shoot. Its even simple to use, put one on your cameras hot shoe, slot your Nikon (generic) flash into the hot shoe of the other Yongnuo transmitter and basically fire away. So you probably asking well then why are they so cheap at around R900 for 2, compared to the PocketWizard setup at R5000 for ONE TT5 or TT1. Let me explain… The Yongnuo RF603 as great as they are do have a few short comings. They do not use TTL and are not high speed sync compatible. Yes even if your camera and flash can are High Speed Sync compatible, when you take your flash off camera your shutter will only sync to a maximum of 1//250 on a Nikon and 1/200 on a Canon. As for the TTL, you need to operate each flash manually. This isn't a bad thing, but if you need fluidity at a shoot or wedding, you best get yourself an assistant that knows how to change the power up or down on your flashes. A lot of photographers don't like TTL as it isn't always accurate but lately I have found it to be pretty decent and reliable with the SB-910 and PocketWizard TT1 and TT5 update. So if you looking to get your flashes off camera and change your photography style and don't have a massive budget you definitely can't go wrong with the Yongnuo RF603, high speed sync can easily be over come by using a lower aperture (e.g. f9 etc) to decrease the amount of light your lens lets through. I do believe Yongnuo has new TTL and High Speed Sync transmitters and are a little more expensive than these, but still way cheaper than the Pocket Wizard System. Read my PocketWizard review to see why I still rate it the best wireless system out on the market event thought some of the new Yongnuo's have TTL!