Examples of image configurations formed by four ellipsoidal NFW lenses. Each of the four pairs of panels shows the position of the source with respect to the caustics (left), and the positions of the images with respect to the critical curves (right). Images are plotted for two source sizes (red, yellow); in the bottom right example a third size is added (blue). Lens parameters (κ_s, e) for top left example: (0.25, 0.9); top right: (0.398, 0.9); bottom left: (0.5, 0.9); bottom right: (40, 0.9986).