Top: Surface gravity vs. T_eff for observed He WDs with WD companions (P<0.1 day), likely from the CE channel (Brown et al. 2020). The color bar indicates the orbital period. Middle: Same systems evolved to the merger time, assuming the minimum initial M_H (no H burning). Bottom: Same as the middle panel, but with the color bar indicating WD age at merger. He WDs with P≳0.07 day are expected to merge at T_eff<8000 K, reaching ages of ∼2 Gyr.