Right: BT-Settl and BT-Dusty models for an effective temperature of 2900 K and varying log g. The effect of gravity and the pressure broadening of the K I doublet is clearly visible. The details of the dust treatment only cause negligible differences at this T_eff. Left: K I doublet as observed for the primary (black) compared to the BT-Dusty (red), BT-Settl (green), DRIFT (blue), and MARCS (brown) models with log    g = 5.0.