Maximum radius R_MAX ratios as a function of ZAMS mass M_ZAMS between the reference metallicity Z = 0.1 Z_⊙ and the other adopted metallicities according to our MESA simulations. We show the R_MAX(0.1 Z_⊙/R_MAX mean value at ∼1.1 and its Gaussian distribution up to 2σ. The variability of all the low-Z models with respect to 0.1 Z_⊙ sits within 1σ, while it gets significantly beyond 2σ at Z_⊙ for M_ZAMS≳ 60 M_⊙ due to the increasingly large effect of wind mass loss and the treatment of superadiabaticity.