We have the patio door model also: here's a link to what it looks like
http://www.petsmart.com/global/produ...=1128456201812
I love it and I think they do too, because they spend all their time running in and out.....just like little kids. We have a fenced in yard but not covered, so we are careful to keep an eye on them because of coyotes and hawks that we have around us. The panel is closed at night, I get too nervous. And then in the winter we take the door out.
It didn't take long at all for them to learn how to use it. Even my new Biewers are old pros at it. Leo even takes toys out with him. It was funny to watch him attempt to take a dish out. Of course it won't fit, but he tries once in a while.