Color–magnitude relation for the whole sample of clusters considering different cluster areas. On the x-axis the integrated V-band absolute magnitude within r₂₀₀ is indicated, and on the y-axis the average of all the integrated colors within the considered radius, plotted in the lower left corner of the panel, is indicated. The gray dashed line gives the average red sequence slope observed for the CM relations of the galaxies of the WINGS clusters derived by Valentinuzzi et al. (2011). The average red sequence slope is plotted by matching the intercept of the line to the mean color of the distribution. The bold dashed line is the WLS fit of the observed distribution.