Distribution of the pre-SN helium core mass of SN II progenitors in case they experienced isolated evolution (black dashed line) or have followed a channel of binary interaction (red solid line). The contribution of each different binary scenario is also shown (dashed and/or dotted lines). The equivalent single-star initial masses corresponding to each M_He, preSN (inverse of Eq. (1)) is shown on the top x-axis. The results are for our standard assumptions and show the number of SN II per logarithmic bin in M_He, preSN per solar mass of star formation.