Normalized growth rates η for ℓ = 1 modes in terms of the pulsation periods for 0.1868 M_⊙ pre-WD models at T_eff ~ 11 400 K (upper panel) and for 0.1921 M_⊙ pre-WD models at the same T_eff (lower panel). Different symbols connected with thin lines are associated with models with different He abundance in the driving region, including that with canonical He abundance and those models (artificially modified) with increasing X_He values in that region (see text). The large numerical range spanned by η is appropriately scaled for a better graphical representation. The vertical dashed lines correspond to the periods at ~381 s, ~406 s, and ~421 s observed in WASP J0247−25B.