full color white balance disc has high precision,the disc can help to restore original color of objective,there is a gray card in the back to perform a precision correction of all of the colors in the scene.
The White Side
The White Side is designed using a specially fomulated grooved board over a reflector lens, covered with a condenser, to give accurate color balance in mixed lighting situations, low light, or on cloudy and overcast days.
The Grey Reverse Side
The Grey Reverse Side is formulated from a secret combination of thirteen different materials which have been tested to produce the most consistent color balance and is best suited to studioflash photography and direct sunlight.
