Panel a: differential distribution of lengths for the sample of 599 robust HGBS filaments identified by Arzoumanian et al. (2019). The red curve shows a lognormal fit to the overall distribution, the black solid line segment a power-law fit for filaments longer than 0.9 pc. Panel b: total mass M_tot against average mass per unit length M_line for the same sample of filaments as in the top panel. A strong linear correlation is observed between log M_tot and log M_line (with a Pearson correlation coefficient of ∼77%). The red line shows the best-fit linear relation, M_tot = M_line × L_eff, consistent with a typical effective length L_eff ∼ 0.55 pc in the filament sample of Arzoumanian et al. (2019).