Comparing the derived [Fe/H] from the SAPP for M dwarf secondary components in a binary (y-axis, Table 2) with the metallicity of the primary (x-axis, Table 4). The blue circles show binaries with an FGK-type primary and an M dwarf secondary. The orange squares show binaries with a KM-type primary and an M dwarf secondary. All stars in these three systems were analysed with the SAPP using APOGEE spectra. The black dashed line corresponds to the 1:1 ratio.