Package List:1 x Black Card and 1 x White Card and 1 x Gray Card and 1 x Portable Strap. | 3 in 1 Color: Standard 18% white, black and neutral gray three color calibration reference cards to help you get the right color balance. | Functions: Determine exposure value, determine light ratio, determine color balance and density and exposure for reproduction photography, set white balance for digital cameras and camcorders. It is the ideal accessory for portrait, flower, reproduction and other photography. | Easy to carry: Neck strap design, hanging on the neck, carry around. Quick-release plastic clasp at the end makes it easy to use the card. | Application: Suitable for handheld metering meters, cameras, movies or digital.