Thank you for the pointers, gentlemen. I should add that the "acceptable" stability of my old steel chair means that I have only fallen a couple times from it over the years, and, thanks to the same grass or snow that makes it unstable, softly. The tallest Cat's Perch and Walts, being a foot taller and having a similar footprint, don't look good to me. The observer demonstrating the former has a paved area - good for him!