The median radius r_med of a deprojected Sérsic profile normalized by the scale length a when the enclosed mass is equal to half of the total mass (i.e., the intersections of the curves in Figure 1 with the horizontal line at 0.5). The top panel is for spheroidal shapes, either oblate axisymmetric (q < 1) or prolate axisymmetric (q > 1), and the bottom panel for fully triaxial shapes. In all cases, r_med/a depends on the intrinsic shape, but only mildly on the Sérsic index n.