Andoer 3 in 1 Pocket-Size Digital White Black Grey Balance Cards 18% Gray Card with Neck Strap for Digital Photography Includes three color calibrated reference cards. It helps you get correct white balance, or color balance, allowing the camera to compensate for the illuminant color in a scene. For optimum color correction: the black card achieves truly deep blacks (RGB 16,16,15); the grey card displays superior spectral neutrality with measured values of 162, 162, 160; the white card has a tested RGB value of (220, 224, 223). The neck strap with quick-release plastic buckle on the end, convenient for your use.