PoWR spectra in the optical region of TWUIN stars with different M_ini (see labels on the right side of the panels) and in different CHB evolutionary phases marked by the value Y_S in the colored boxes. The mass-loss rates are taken from the stellar evolutionary calculations (i.e., higher Ṁ). Colored lines correspond to the clumped wind models (i.e., D = 10), while the black lines correspond to the smooth wind.