This tray can be placed on almost any flat surface and even on top of a cage if it is flat. (petbusiness.com)
Easily slips over top of cage creating a relaxed, cozy environment that reduces stress and promotes healthy, sound sleep. (puppeepoopalace.com)
Some cages offer the addition of flip top lids that open the entire top of the cage in addition to doors, which provides another easy access point. (northstarrescue.org)