Observed mass-loss rates vs. wind velocities of M-type AGB stars (Olofsson et al., 2002; González Delgado et al., 2003, plus signs) and the corresponding properties of all models which develop a wind (indicated in red in Fig. 1). All panels show the same data but with different colour coding according to stellar luminosity (upper left), effective temperature (upper right), seed particle abundance (lower left) and piston velocity amplitude (lower right). The stellar mass is one solar mass for all models.