Currently, I recommend the Cat Mate Large Cat Door White on Amazon.

We had a smart cat door in our garage for our cat Missy the Siamese Wolverine. It required that she have a small identification disk on her collar. It allowed only her to come in and go out; other cats and critters (like raccoons) could not get in. It was programmable; I programmed it to let her in at any time but not to let her out at night (from dusk to dawn).

This device is especially comforting when you are on vacation and have a pet sitter or neighbor looking after your cats. Our neighbor would let Missy out in the morning and she would be in the garage in the evening. It helps maintain the most important rule of protecting your cat from coyotes: cats stay in at night.

Warning: The older model we have is not easy to program. If you order one and find it is difficult to program, find a geeky person to do it.