Production factor of selected isotopes for the low metallicity models of 7, 5, and 3 M_⊙. The Z = 10⁻⁵ results (black) are compared with the Z = 10⁻⁴ calculations (orange) of Karakas (2010) for the 3 M_⊙ and 5 M_⊙ cases, and Doherty et al. (2014b) for the 7 M_⊙. Results are also compared with the Z = 0.001, 3, and 5 M_⊙ models by Fishlock et al. (2014) and with the 7 M_⊙ model by Doherty et al. (2014b). All models were calculated with the same Vassiliadis & Wood (1993) wind prescription (VW93), except for the ones shown with dotted and dashed lines, which were calculated with Reimers (1975; Rei75) and Bloecker (1995) with η = 0.02 (Blo95).