(a) Mean intergalactic transmission for a source at redshift z = 3.5 (solid lines). The mean intergalactic transmission assuming no Lyman Limit Systems lie along the line-of-sight is shown by the dashed lines. (b) Mean intergalactic transmission for, from left to right, sources at redshifts z = 2.5, 3.5 and 4.5. The heavy lines are the estimates from Meiksin (2006). In both panels, the light lines are earlier estimates from Madau (1995).