QPcard 101 is a neutral reference card perfect for gray or white balancing. It has three patches, white (Lab 95*0*0), mid gray (48*0*0) and dark gray (35*0*0).The spectral respons of the three colors is almost perfectly straight, meaning no problems with metameric effects.The colors are extremely fade resistant. The main purpose with the card is to use the gray patch for neutral gray balancing of the image. The gray patch is reflecting 18 % of the light, making it useful also for exposure purposes. Since the white patch is free from fluorescent whitening agents, it is perfect for custom white balance setting of your camera before shooting. There is a millimeter reference scale along one side of the card.The card is self-adhesive making it perfect to place on almost any surface in the scene. The size of the card is 142 x 40 mm (5.6 x 1.6″).