Left: concentration–mass relation obtained for the final cluster sample in the case Δ = 200 (black diamonds). The cluster total masses are obtained following the backwards method described in Ettori et al. (2002). A NFW profile is adopted to describe the gravitational potential. We overplot the c₂₀₀ − M₂₀₀ relations predicted by P12 (yellow lines), DM14 (blue lines), and DK15 (red lines). They are calculated for z = 0.4 (dotted lines) and z = 1.2 (dashed lines), which are the lowest and highest redshifts in the sample. Right: the same as the left panel, but here the sample is divided into 7 mass bins. For each bin, error-weighted means for concentration and mass are calculated (black diamonds) and the error bars represent the errors on the weighted means.