λ _∥/( Rl ₀) vs. R for δ B/ B ₀ = 10.0, 50.0, and 100.0 plotted as circles, stars, and squares, respectively, for the slab model validating the relation of λ _∥/( Rl ₀) ~ B ₀/δ B. Dashed lines from top to bottom correspond to the right hand side of the latter relation, that is B ₀/δ B = 0.1, 0.02, and 0.01.