HRD with the WC & WO star positions compared to a BPASS binary evolution track. Only the evolution of the primary is shown, as the secondary has a way lower mass and remains on the main sequence at logL/L_⊙ ≈ 2.2 during the whole lifetime of the primary. For comparison, also the corresponding single star evolutionary track for the primary is shown as a dashed line. The different colors indicate the different WR phases, defined via surface abundances.