The Lee Color Print Viewing Filter Kit is used to calculate the color balance of a transparency or print. It features six cards, each with 3 viewing filters.These color print viewing filters are used between the light source and the negative or transparencyEach of the six cards in this kit is for the compensating filter color like the cyan, yellow, magenta, red, green, and blueEach color has filters with required densities and are arranged in a particular order around the central clear filterThese color print viewing filters are also used in calculating images and to adjust exposuresYou can easily identify these color compensating filters by viewing through the card