I forgot to get a picture of hole #3, but I can assure you it also worked well. The cats weren't phased by it. It was slightly bigger than hole #2 and, well, slightly smaller than #4.
Hole #4 is frightening.
Below is Hole #4. Litter falls in the toilet like at waterfall. Litterfall? Whatever, I'm just glad I haven't, so far, had any plumbing problems. The cats have not used this yet. I just "installed" it. Wish me luck.