Illustration of the relevant observed features mixed with the theoretical prediction of a continuously expanding and recollimating flow (e.g., Daly & Marscher 1988; Gómez et al. 1997) with an entrained particle distribution of downstream decreasing density. The straight lines indicate Mach cones for different speeds of the flow. Standing features observed at 43 GHz and 86 GHz are interpreted as the first recollimation shock downstream of and in close vicinity to the cores atthese frequencies. Its distance to the black hole is unknown for 3C 111. At 15 GHz, we observe a second recollimation shock at a distance of 3 mas from the core component at that frequency. We detect no signs for further recollimations. Overlaid, we plot the EVPAs from the stacked image in Fig. 6. The orientation of these EVPAs appears to be perpendicular to the jet in absence of the recollimation and parallel on top of it.