We currently use So Phresh litter boxes. We came across it after trying out a few other brands. Most were too small, the wrong height, or not as durable. So Phresh cat litter boxes come in different sizes and can be configured to your specific need for your cat. You can use just the bottom, or add a privacy hood or a rim to customize it. It also fits the cat box liners that we love (Johnny Cat) because they are very durable and strong.