Dynamical mass-to-light ratio as a function of the absolute magnitude in I-band. Red and blue dots indicate our pressure and rotationally supported dEs respectively. For comparison, open circles show dEs by Geha et al. (2002, G02), grey asterisks are dSphs from Wolf et al. (2010, W10), and dark and light grey triangles are slow and fast rotators from Cappellari et al. (2006, C06). The transformation to I band was performed using the colour-morphology relation by Fukugita et al. (1995) for Es. For the dwarf galaxies we used V − I = 1.03 ± 0.04 as calculated by van Zee et al. (2004a).