The only gray card specifically designed to be used in digital photography. The RMI Digital Gray card avoids color casts regardless of lighting, and provides durability versus other traditional gray cards.Spectrally uniformDurable plastic material Waterproof WashableRepairableNote: The Digital Gray Card is designed for digital photographers only, as it is not an 18% gray. Reflectance is 30-37% (based on the light source) which will create inaccurate readings with film camera light meters.