Four plots showing the discriminatory power of the combination of an HST broad-band filter (F125W) with a narrow- or medium-band one for the standard stars in SPLAT: F126N (top left panel), F127M (top right panel), F128N (bottom left panel), and F130N (bottom right panel). Most extra-galactic observations feature the F125W. This is to show which medium- or narrow-band filter should be added to that to improve the (sub)typing of the brown dwarfs in these fields. All work well (ρ > 0.90) but the F127M stand out as an excellent compromise with a monotonous relation between the F125w-F127M color and type and highest throughput of all the considered narrow/medium bands.