Distribution of GC metallicities. Top row: Full sample of GC metallicities (shown in grey) combining the measurements from Alves-Brito et al. (2011) (black, first panel) and the ones presented here (blue, second panel). Third to fifth panel: GC metallicities from OSIRIS (green), MUSE (orange), and FLAMES (purple). Bottom: GC metallicities in different radial bins. The lines show kernel density estimations scaled to match the counts. The small vertical lines near zero indicate the individual metallicity measurements.