Cal wrote:

: I have 2 kitty doors. 1 to the garage and open the screen porch in the
: slider. I got the medium size. I have a large baby 22lbs and I was
: paranoid he wouldn't fit in the door and get stuck. The other cats
: open it just fine.

Thanks Cal. You didn't specify if it is Petsafe Ultimate? The medium
size in this line has an opening 8" wide. I would not worry about that.
I am considering small size, to keep out raccoons etc. The opening is 4
1/4" wide. That's what I am trying to determine, if it would
accommodate average cats.

Petsafe also has a Classic line. The small size theer has an opening 5"
wide, a little better.

However, Ultimate is their best line, so if some experienced person
would say cats can squeeze through 4 1/4", I would get that.