F814W − K_s vs. K_s − [ 3.6 ] colors for the ALMA-FFs DSFGs (red symbols, both panels). On the left, we compare to 22 ALMA-detected submm galaxies (SMGs, black circles + crosses) and 142 non-SMG field sources (black crosses) presented by Chen et al. (2016, C16). The nominal OIRTC cuts adopted by C16 are denoted by the dashed region. The ALMA-FFs DSFGs appear systematically offset from the C16 sample by 0.6–1.0 mag in K_s − [ 3.6 ], likely due to different aperture correction choices. On the right, we compare 11 ALMA-FFs DSFGs to 767 non-stellar >5σ sources from the AstroDeep F160W catalog (black crosses) in the ALMA footprints of the A2744 and M0416 clusters. Following the prescription in C16, we recalibrate the OIRTC color cuts for the AstroDeep sample, which are again denoted by the dashed region. In both figures, the 11 objects with detections in K_s are plotted; two objects, namely A2744-ID04 and M0416-ID04, have similar colors and therefore lie on top of each other in these figures.