Model atmosphere grid dimension in the T_eff−log g plane (black line). The grey band denotes the EHB for solar composition (Dorman et al. 1993) for comparison. The helium main sequence (Paczyński 1971) is shown in red with masses labelled. The dashed line shows the Eddington limit for solar composition (Lamers & Fitzpatrick 1988). Grids are constructed at metal compositions of 1/100, 1/10, 1 and 10 times the standard sdB metallicity pattern and n(He)/n(H) of 1/10 000 to ≈100 times solar, depending on metal content.