Comparison of the PL and PW slopes of the BL Her models as a function of chemical composition (Z1 = 0.01300, Z2 = 0.00834, Z3 = 0.00424, Z4 = 0.00135, Z5 = 0.00061, Z6 = 0.00043, Z70.00014) across different wavelengths for the convective parameter sets A, B, C, and D. The horizontal lines represent the mean values of the slopes in the individual sub-plots. The y-scale is same (1 unit) in each panel for a relative comparison.