Colourright Pro is a colour balance tool designed to be used with any D-SLR. It makes it easy to get the colour balance right every single time you shoot & saves hours of fiddling about afterwards. The idea is very simple you place the colourright filter over your lens take a reference shot & set the custom white balance to reference the shot you just took. It takes about 15 seconds on most D-SLR s & from then on every shot taken in that setting will be completely neutral. It works with pop-up flash & external hot shoe mount flashes. (the only tool of its kind that works simply & easily with flash). colour Right Pro gathers light from multiple angles ensuring you are getting the whole colour picture. It is designed to be used in the easiest way possible by simply pointing toward your subject. Most colour aids insist you measure the light at the subject location- which requires a lot more time & effort. It is guaranteed to be spectrally neutral to a very tight tolerance. It transmits more of the light than the nearest competitor.