Period-mass ratio relation of the sdB binaries produced by the different MESA samples. The grey squares show the real observed systems, while the blue circles show the MESA models which would have been observationally identified as composite long-period sdB binaries, i.e. fulfil the visibility criteria in Sect. 5.2. The observed systems, located within the nearest 1 kpc, belong to the solar neighbourhood. Most of the simulated sdB binaries in the Galactic population belong to the thin disc, which is the dominant Galactic component (see Table 2).