Rest-frame velocity distribution of all the spectroscopically confirmed cluster members (including those outside R₂₀₀). The red-shaded histogram is for the red-sequence galaxies, while the blue-hatched one is for the blue population. The velocity dispersion of the total population is represented by the Gaussian curve, which is centred on 0. From left to right, top to bottom: RXC J0014, RXC J0225, RXC J0516, RXC J0528, RXC J0658, RXC J1131, RXC J1206, RXC J1347, RXC J2011, and RXC J2308.