RGB images of the cores of the four clusters from HFF photometry. The red, green, and blue channels were obtained by combining the filters F105W + F125W + F140W + F160W, F606W + F814W, and F435W, respectively. We show the FoV of the MUSE observations with red contours, and we mark all the cluster members for which we have measured a velocity dispersion value with green circles. Finally, we show the region intersection of all HFF bands for each cluster with cyan contours.