Innovative, self-contained waste drainage system makes it easy to leave your pet at home alone without worry. Artificial grass will not stain or discolor and won't slide off the potty. Dogs feel comfortable walking in and your flooring is protected by built in splash guards. Collector tray is easy to clean and empty. Replacement grass available; swap grass once a week so you don't have any downtime for cleaning. Mini is for toy dogs; medium for smaller dogs. Shipped directly from manufacturer.