The ColorChecker Gray Balance is the largest size available Gray balance card in the range, it’s the same size as the ColorChecker Classic Target at 215.9 x 279.4mm. Using the ColorChecker Gray Balance card for reflective spot exposure metering will give you the confidence that your images will be exposed as accurately as possible. The ColorChecker Gray Balance card is the larger size version of the 18% grey reference square in the standard 24-patch ColorChecker. The grey is scientifically engineered to provide a precise uniform surface that is spectrally neutral, meaning it reflects equal amounts of red, blue and green in all types of light conditions.