This is part of a rather large enclosure we have to keep the cats out of harms way. It's covered with wire mesh (including the top). It's the ONLY way to contain a cat. Trust us. We have spent many thousands of dollars with special fences, and other devices to contain them. Sooner or later they would always finally figure a way around whatever containemnt concept we constructed. They've been in the enclosure for over 5 years and still test it periodically (just in case a hole might magically appear or something). And! The best part of it is no more ANXIETY!