The falcon eyes grey cards are white balance cards, which are used to assist you in getting the colours in your photographs as precise as possible. no matter how advanced your camera is, it is often hard to photograph true-to-life images with a modern slr or compact camera. while most advanced cameras automatically try to calculate the white balance as accurately as possible, the results often leave you with images containing non true-to-life colours and/or a colour cast. a photo can only contain true-to-life colours if your camera knows the exact white balance value. the falcon eyes grey cards are used to obtain this correct white balance value. to learn more about how to use the grey cards, you can download the extensive user manual below. Falcon eyes grey cards specifications The grey cards are delivered in a set of 2 with both cards having a different size. the 2 different sizes make it suitable to use the grey cards on any location. the cards are made of a durable, scratch and water resistant, material and are easy to use. the grey cards are suitable for use with raw, jpg and tiff photographs.