This arrived quickly and was very easy to assemble.? I put all the shelves going in one direction next to kitty's larger sized shelving.? She can climb up and sit in the window and look outside, but she can definitely not stretch out and take a nap on these shelves (which I was slightly disappointed about)..? She's 14 lbs, and can just about sit comfortably on the shelving.? For naps, she needs to return to the larger shelving.? (But she's apparently OK with that..!)? A smaller cat would enjoy this even more.? I did secure the very top to the window frame with a small cup hook because it did move a bit, but it's pretty stable.? I don't know yet how it will hold up as a scratching post or "activity center."