The grey scale consists of nine pairs of non-glossy neutral gray-colored chips, which illustrate the perceived color differences. These give a corresponding fastness rating of 5, 4-5, 4, 3-4, 3, 2-3, 2, 1-2, and 1. They are used in the assessment of color change occurring in fastness tests as described in ISO 105-A02. They are also essential in the grading of light fastness tests when using the light fastness standards.