Spherical degree plotted as a function of the lower turning points of the oscillation modes. The shaded area indicates a range of ±4Δν around ν_max of the models indicated in the legend. The data for the red-giant model used in the inversions are shown in dark grey whereas the data for Model S are shown in blue. The more evolved red-giant model is shown in orange. The base of the convection zone is indicated with a dashed line. In the more evolved model the base of the convection zone is not visible on the given scale.