Relation between the total mass and the full DM halo shape parameters, s_DM and T_DM, for the Magneticum sample used in this work (black), a set of six DM-only simulations (red, Allgood et al. 2006), and the Millennium simulation (blue, Bett et al. 2007). The solid lines indicate the median values in the respective mass bins and the shaded regions the 1σ ranges (containing 68% of the galaxies above and below the median). The blue dashed lines mark the halo masses corresponding to less than 300 DM particles in the Millenium simulation. The dashed part of the black lines indicates where there may be effects caused by low number statistics.