ColorChecker Mini Gray Balance card is a pocket size version of the 18% Gray reference square used in the standard 24-patch ColorChecker. This Gray is scientifically engineered to provide a precise uniform surface that is spectrally neutral (reflects equal amounts of red, blue and green) in all types of light conditions. The photographer can now have confidence that the camera's raw image is as close to real life as possible. Even in a controlled studio environment, establishing an accurate custom white balance ensures an accurate image from the start of each new photo session.