Parametric redshift distribution of sources with i₈₁₄> 22 (upper panel) and the corresponding distribution in lensing efficiency β (lower panel). In the upper panel, the dashed green line corresponds to z_eff ≈ 0.88 with respect to SG1120 and the dotted red line corresponds to z_eff ≈ 0.95 with respect to the two structures at higher redshift. In the lower panel, the dashed green curve shows the distribution in β with respect to SG1120, with ⟨β⟩ ≈ 0.52 (dashed green vertical line), and the dotted red curve the distribution in β for the two structures at z = 0.48, with ⟨β⟩ ≈ 0.42 (dotted red vertical line).