Designed for a bird s well-being. Helps keeps debris and fragments from falling outside the cage. Holds treat sticks and bars. Your bird will enjoy getting the food off the stick and the action will also help trim the beak. Designed for a bird s well-being. Helps keeps debris and fragments from falling outside the cage. Holds treat sticks and bars. Your bird will enjoy getting the food off the stick and the action will also help trim the beak.. Plastic.