Compact Symmetric Objects in a complete flux density limited sample

This paper discusses the content of Compact Symmetric Objects in flux density limited VLBI surveys. We present new multi-wavelength VLBA observations confirming the CSO classification of some objects and two epoch 4 cm global VLBI observations from which we measure the hotspot expansion velocity in a CSO and confirm the expansion velocities previously measured at other wavelengths for 3 other CSOs.