Contour levels of initial orbital periods, P_i, allowed by stable MT with ϵ = 1 efficiency, if the period at detachment is imposed to be P_r = P_today from Table 1 and the reference mass ratio is q_r = 10.5. We populate the lines of constant total mass at the present-day with MESA simulations, represented by their outcome with color-coded pixels. If these simulations reach a mass ratio at detachment q_detach such that q_detach ≥ q_r, we mark them as hits (blue edges). This is shown as a function of stripped and Be star initial masses, m_{stripped, i} and m_Be, i. The black region indicates initial mass ratios of q_i > 1, and the solid black line delimiting the base of the contour plot corresponds to q_i = 0.25; i.e., the lowest mass ratio we evolved.