Range of variation in peak ionizing photon fluxes across the grid of models considered here. Range is shown separately for each metallicity, first for single-break IMFs with M_u = 300 M_⊙ and varying α_m = α_l, then for models with fixed α_m = α_l = −2.35 and varying M_u, and finally for double break models with α_m = −2.35, α_l = −2.00 and M_u = 300 M_⊙ but varying M_m. All ranges are shown relative to the BPASS default IMF model, which is a single break power law with α_m = α_l = −2.35 and M_u = 300 M_⊙.