Mass–radius relation from the spherical collapse model. Different lines correspond to the masses for different density contrasts, Δρ (Eq. (1)). Lines M₆₀ − M₃₀ correspond to the density contrasts, Δρ_inf, at the borders of the spheres of influence as found for clusters. Lines M_13.1, M_8.73, and M_5.41 corresponds to the turnaround, future collapse, and zero gravity density contrasts. All lines are calculated for the redshift z = 0.03.