Surface rotational period versus mass. Comparison of the models (diamonds) at three different initial velocities: slow (cyan), median (blue), and fast (violet) with the observations for open clusters at different ages and metallicities. The orange diamond for Pleiades corresponds to a slow rotating model at 125 Myrs. In the case of αPer, Hyades, Praesepe, and NGC 6819, we also show the predictions of the models (magenta diamonds). Observations’ references are reported in Table 1.