If you reading this review you probably have a big budget to spend and you really keen on taking your photography to another level! All I can say is this is the best system around! I previously used the Yongnuo RF603 transmitters for sometime before I built up the budget for the ultimate Pocket Wizard setup. The Yongnuos weren't bad, but wow, once you've used a Pocket Wizard system you won't go back. PocketWizard Mini TT1 This is a transmitter, it only transmits signal, its a lot smaller than the TT5 and looks much neater on the hot shoe of your camera. It does take a flat "watch style" battery (CR2450) but these batteries are cheap (around R45) and last a long time and can be found at your local store. You have the basic Off, Channel 1 and Channel 2 switch on the side with a test button. PocketWizard makes a cable that runs from your camera to the TT1 allowing it to feed off your camera battery. PocketWizard Flex TT5 This is a transceiver, it is able to transmit and receive signal, so basically you don't need a Mini TT1, as you can use this on your camera as a transmitter, the only down fall is the size and the aerial. These take 2 x AA batteries (I use the Uniross 2700mah and get great battery life out of them). You have the basic Off, Channel 1 and Channel 2 switch on the side with a test button as well as group A, B and C. Remember these are full blown awesome transmitters, TTL compatible and High Speed Sync so you can shoot up to 8000th of a second without missing a pulse. So before I confuse you with the AC3, lets do a basic set up: Lets put our Mini TT1 on a D800, and we put a SB-910 on the Flex TT5. We put both TT1 and TT5 on Channel 1 and the TT5 is set to group A. We could stick another SB-910 or SB-800 even on a second TT5 also on Channel 1 and for arguments sake, lets put this one in group B. We can now shoot on whatever mode on our camera (Manual, Aperture Priority etc) and the PocketWizard system will measure everything in TTL for us and output the desired light. Behold...the AC3 Controller This is a very basic plastic controller that slots on top of your Mini TT1 or Flex TT5 that is mounted on your camera.. On the AC3 you will see you have 3 groups, A, B and C. These are the same groups on the TT5. You can switch any group on or off at any point without having to physically go to that flash or device. You are also able to toggle manual mode (M) or TTL (A) by the flick of the button for each group separately. The little dials with the numbers on allow you to adjust your flashes power (manual mode) or exposure compensation (TTL or Auto mode) by scrolling it left or right. White for brighter (more power), black for darker (less power). These adjustments are done in stops. This little controller is so easy I can adjust flashes whilst having the camera at my eye walking backwards or forwards during dancing shots. Im sure you have started putting this all together by realising how fluid and easy this could make your shoot or wedding. There is no need to run to your flash at the back of the hall/church or model to manually adjust the power, now you can do so by just scrolling a wheel. So yes this is the perfect wireless transmitter system and if you have the budget for it, buy it!!!! BUT, PocketWizard please could you explain to me how a R5000 TT5 or TT1 can have a plastic hot shoe that ALWAYS breaks?? This is the only downfall and complete pain in the butt if your plastic hot shoe breaks and you can't use a light stand because you have no way to lock your TT5 in. Lets just hope they fix it on the next model or they manufacture metal hot shoe replacements, if Yongnuo can do so at a 10th of the price, I don't see why PocketWizard cant.