Dynamical mass-luminosity relation for sub-stellar objects detected in the BPMG. The solid red and the dashed green lines are averages of the predictions by models of Mordasini etal. (2017) forages of 20 and 10 Myr, respectively. The shaded red region between the dotted red lines represents the range of values that are expected for a 20 Myr age, depending on the peculiar evolution of individual objects.