End PMS evolutionary critical points in bolometric magnitude as a function of age, in Z = 0.002 (blue) and Z = 0.014 (orange). The size of the symbols is proportional to the corresponding initial mass of the model. The mass of some of the points is explicitly indicated in the plot with a black circle. This plot shows that at a given moment, in the lower metallicity population, the stars at the end of the PMS phase have a lower initial mass, and therefore a lower luminosity. This creates the shift we observe in the H-peak positions predicted by the lower metallicity models.