Mass of the gas discs (deep blue circles), thin discs (blue circles), thick discs (orange circles), and CMCs (red circles) as a function of the galaxy circular velocity. Red arrows indicate galaxies for which no significant CMC is found. Red circles in large green circles indicate unresolved CMCs, red circles in large dark orange circles indicate classical bulges, and simple red circles correspond to pseudobulges. Deep blue arrows indicate galaxies for which the 21-cm flux is not available. Crosses indicate boxy/X-shaped inner structures that are superimposed onto a given CMC. The vertical dashed line corresponds to v_c = 120 km s^-1.