BH masses in BH-BH mergers within design advanced–LIGO sensitivity (z <  2) for models M10.B (that employs old average metallicity cosmic evolution) and M60.B (new average metallicity evolution). BH masses are calculated with the same formulas in both models. Top panel: distribution of individual BH masses, bottom panel: total BH-BH system mass. All distributions are intrinsic (not redshifted nor weighted by detection probability). We note that application of new metallicity evolution with redshift (less low-Z stars: less high mass BHs) results in somewhat steeper BH mass distributions as contrasted with application of old metallicity evolution (more low-Z stars: more high mass BHs). Power-law fits (dashed black lines) were performed for both models in the log-log space.