Access OTech 3 in 1 Digital 18% grey/white/black card set photography lighting balance bracelet – Ideal for addjusting in either dark or light environments – The Grey Card can blaance all mixed lights to 18% neutral grey – Use of a Photometers the exact exposure value, by reflecting the light of the records on the grey card – Adjustable the color balance and revert the color by controlled the gray balance – Scratch Resistant Waterproof cards