Mock images in the r-band of example galaxy clusters from the Magneticum Box2 hr simulation in a random projection, with increasing mass from left to right and cluster IDs indicated in the top left. Clusters in the left column have about M_200c = 1 × 10¹⁴ M_⊙, with clusters on the right having M_200c > 1 × 10¹⁵ M_⊙. From top to bottom we plot galaxy clusters with decreasing BCG stellar mass (within 100 kpc, excising satellites) within a narrow bin of cluster halo mass. Each panel shows the full R_200c size of the cluster, with the black line in the bottom left of each panel marking the effective length of 100 kpc while the axes ticks are in units of 0.2r_200c.