Properties of the selected targets. Symbols and colors are explained in the legends. (a): Color-magnitude diagram of the studied sample. For reference, we plot the white dwarf cooling tracks for He-, CO-, and oxygen-neon (ONe)-core white dwarfs (Althaus et al. 2013; Camisassa et al. 2016, 2019) and the isochrones, which we converted to the Gaia magnitudes by means of synthetic spectra (Koester 2010); the corresponding masses, in Solar units, and cooling ages are labeled. The solar metallicity BaSTI isochrones with [Fe/H] = +0.06 (Hidalgo et al. 2018) are also plotted at 1 and 10 Gyr (dashed and solid curves, respectively). (b): Projected velocity difference plotted against projected orbital semi-major axis of the studied binaries.