Spectral age profiles of the three RGs made along the slices marked in Figs. 3, 4, and 5, and the complementary error maps. Each panel is labeled from a to c in the top-left corner. The points, where χ_red² is high (marked in red in according panels in Figs. 3, 4, and 5) were omitted. Panel a: Spectral age profile of J1021+1216. Points mark the measurements taken from the low-resolution maps, squares mark the measurements taken from the high resolution maps, and the star marks the CI spectral age of the core extension modeled with integrated flux densities. Black lines mark the best-fit constant-speed expansion model of the outer lobes. The fit was made using the low resolution data. Panel b: Spectral age profile of J1528+0544. Points mark the measurements taken from the low-resolution maps, stars mark the points excluded from the fitting, and squares mark the CI spectral ages of the inner lobes modeled with integrated flux densities. Black lines mark the best-fit constant-speed expansion models of the outer lobes. Panel c: Spectral age profile of J2345–0449. Points mark the measurements taken from the low-resolution maps, and squares mark the spectral ages of the inner lobes, which were modeled as single regions, at the positions of their hot spots. Solid lines mark the best-fit constant-speed expansion model of the outer lobes.