Kernel density estimation of marginal 3D velocity distributions for various stability filter criteria. The individual lines are color-coded by the filter criteria and range from red (stability < 4%) to dark blue, which represents the strictest filter criterion. The distributions are sampled at constant intervals in stability with a step size of 5%. The hue change from red to shades of blue indicates the transition from the contamination dominated to the more robust filter regime. In addition, we note a kinematic substructure in the z-velocity distribution which is indistinguishable from other sources in all features except v_z.