Boundary particles, or low resolution particles tracing the large-scale structure. These should not enter the high-resolution region; however, in rare cases this may occur. We show here the level of contamination (B.1), in the main halo of boundary particles as a function of radius from the centre of the halo. Each line shows the maximum contamination for a given number of halos. Thus, for example, half of the halos have negligible contamination (orange line), with 95% of our clusters having less than 2% contamination at 5 virial radii (dark red line).