Distribution of photometric metallicity for RRc stars observed by TESS and analyzed by Benkő et al. (2023). Yellow bins correspond to all RRc stars. With different line colors and types, we plotted stars that have additional signals detected as indicated in the key. The f₆₁, f₆₃, and f₆₈ refer to the respective signals, while RR_0.61 represents all RRc stars that show any signal that suggests the presence of the non-radial modes (l = 8 or l = 9). This means the inclusion of f₆₃, f₆₁, f₆₂, and their sub-harmonics and combinations frequencies. Note: metallicity values below −2.7 dex or above −0.3 dex are results of extrapolation and, therefore, should be treated with caution.