Top-entry configuration has a few advantages over front-entry configuration. If your cat scratches and scatters litter everywhere, or your cat sprays or pees sideways, top-entry will be your best bet. The top-entry liner is 14.5" (36cm) tall, and solid around the whole perimeter, this will ensure that anything your cat throws at it remains inside the box, where it belongs. If your cat is obese, elderly, disabled, or just stubborn and refuses to try top-entry, we've got ya covered too. We have a front-entry liner that is also 14.5" (36cm) tall and is solid except at the opening. At the opening, we've provided a walk-off platform that keeps litter scatter at bay.