Contribution of the γ term (metallicity effect) obtained from the theoretical PLZ relations for BL Her models computed using the convection parameter set A across the bolometric (Bol), Johnson-Cousins-Glass (UBVRIJHKLL′M) and Gaia (GG_BPG_RP) passbands. W_Gaia represents the Gaia Wesenheit magnitude W(G, G_BP − G_RP). The different panels present results from the complete set of models compared with the high-metallicity models (Z = 0.00424, 0.00834, 0.01300) and the low-metallicity models (Z = 0.00014, 0.00043, 0.00061, 0.00135). The x-axis is in increasing order of the central effective wavelengths (λ_eff) of the respective passbands as provided by the SVO Filter Profile Service (Rodrigo et al. 2012; Rodrigo & Solano 2020).