Representative velocity profiles of the Hα lines of SNe IIP-CSM for different values of the ratio f_V. The range of each f_V bin is shown above each panel. The spectra are coloured depending on the classification they received in this project: blue for Type IIn, green for Type IInS, and red for Type IIP. As the relative SN contribution increases, the Hα lines become broader, more asymmetric and the absorption component of the P-Cygni profile appears. The flux of the spectra has been scaled for presentation purposes.