N_HI maps of the Reticulum (top) and Eridu (bottom) filaments, smoothed by a Gaussian kernel of 0.3° and 0.2°, respectively, to highlight the cloud edges. The white lines show the perpendicular cuts used to estimate the cloud widths. The cyan squares show lº-wide squares adopted to estimate gas volume densities, B_sky field strengths and parallel diffusion coefficients ĸ_‖ along the filament core.