For Cat fence in people

I'm considering getting the "combination" for my deck. I can't enclose it
(apartment rules) but I *can* attach things to the pickets and enclose the
bottom part (railing) as it can't really be seen. My cats are not big
jumpers, any of them really. This *looks* like a good solution. I don't
think the 20 inch extension would be terribly visible to neighbors. Any
opinions? They would only go out there when I was present.

Karen