Gas mass derived from the dust emission (x-axis) vs. gas mass derived from the CO line (y-axis). We used α_CO = 6.5 to calculate the molecular gas mass from the line, which has been previously converted into assuming different CO-SLEDs (SMG, red filled circles and QSO, blue filled circles), and α_850 μm from Scoville et al. (2016, see right panel of their Fig. 1) to derive the molecular gas mass from the continuum. We accounted for the atomic mass assuming it is 1/5 of the molecular mass. The source IDs are reported in orange. For clarity, we slightly shifted the datapoints of XID 551 toward the left, as they would overlap with those of XID 337 (black shaded symbols). In addition, we report the horizontal error bars of the gas mass derived from the dust emission only on the black open squares. The black dashed line represents the 1:1 relation.