White balance and exposure are the most important things that should be correct in a photo. With the Caruba DGC-2 set of 3 balance cards you can quickly and easily set the white balance of your camera to the situation you are in at that moment. One of the big advantages of this is that you don't have to spend as much time on color and exposure corrections afterwards. A gray card is an attribute that every photographer, amateur or professional, should have in his or her bag!