On the left, we present a Kippenhahn diagram of three SERIES II stellar models as a function of remaining evolution time. On the right, we present a section of the same diagrams but as a function of model number in which the location of some important stages can be seen more accurately. Green hatched areas denote regions of convection. The intensity shown in the colorbar, indicates the net energy rate. Turquoise line shows the CO core. Top panel: structure of a 2.0 M_⊙ helium star with Z = 0.02; η = 0.25 and no overshooting. Middle panel: structure of a 2.7 M_⊙ helium star with Z = 0.02; η = 0.8 and no overshooting. This model evolves into the ECSN regime. Notice that not all of the core is convective anymore due to intense neutrino emission. Bottom panel: structure of a 2.1 M_⊙ helium star with Z = 0.02; η = 1.6 and no overshooting. The ignition of oxygen occurs during the final few hours and cannot be discerned on the left plot.