The fractional mass bias δ_M is shown as a function of local slope α_d and lens redshift z_d (cf. Table 1c). We keep the r-band limiting magnitude for the lenses and the source redshift z_s = 0.99 constant. The top axis indicates the respective lens redshifts in a non-linear scaling. Following the trend seen in Fig. 7, mass is biased low for α_d < 1 and shows large biases for α_d > 1.