The problem isn't really the product, but ZooPlus Customer Support's attitude
I bought the cat tree several years ago, and it held up pretty well until a few weeks ago. My tomcat, K., climbed into the top nest, and at that moment, one of the middle sections gave way and the whole thing broke in the middle of the night. K. fell and got hurt—only luck kept it from being something really serious, otherwise I would have sued ZooPlus. But even so, when I asked them if I could buy a replacement section, they told me it wasn't possible. Very disappointed and dissatisfied.