Abstract: A device and method of keeping litter in an animal cage away from equipment in an animal cage. Embodiments comprise two or more walls to define three zones in an animal cage: an equipment zone, a channel zone, and an outsize zone. The channel zone connects the outside zone with the equipment zone. Baffles in the channel zone permit access by animals but block some fraction of litter from passing from the outsize zone into the equipment zone. Embodiments include a weighing scale in the equipment zone. Embodiments include shapes that constrain devices or equipment to predetermined locations within a cage. Embodiments include methods of use and use in a vivarium.