Standard Dartmouth models computed at the precise masses of the CM Dra stars with [Fe/H] = −0.1 ± 0.1 dex with [α/Fe] = + 0.2 dex. Solid lines show the evolution of models with [Fe/H] = −0.1 dex and the band surrounding those tracks show the predicted variation with metallicity. The lower bound of the uncertainty band corresponds to [ Fe / H ] = −0.2 dex, while the upper band corresponds to solar metallicity. For reference, the horizontal shaded regions mark the observed radius with 1σ uncertainties. The vertical stripe denotes the age constraint determined in Sect. 4, with a vertical dashed line marking an age of 7.2 Gyr.