Example of synthetic horizontal branch together with pulsation models used for incidence rate estimation. The models plotted with gray were calculated with the MESA-RSP code from Paxton et al. (2019). In these models, at least one non-radial mode is unstable. The red and blue line correspond to the red and blue edge for first-overtone pulsations. Synthetic horizontal branch stars are plotted with black crosses when they are outside of the instability strip, in orange if they have unstable first-overtone but stable non-radial modes, and in green when first overtone and non-radial modes are unstable.