R − v_los diagrams and corresponding mass profiles of the two stacked clusters from the CIRS catalogue. The upper (lower) panels refer to the low-mass (high-mass) subsample. The black and red dashed vertical lines show the inner and outer radius of the spherical shell used to estimate the MAR. The shaded areas show the 50% confidence level of the caustic location and of the caustic mass profile according to the caustic technique recipe. The dot-dashed lines show the NFW fits to the caustic mass profiles; the green vertical dotted lines show the upper limit of the radial range over which the NFW fits have been performed.