Works great, but having a metal door, had to cut a bigger opening than the door and then put wood to make a nice finish and make it work great!

We were unable to find a secure outside door to install this cat door into that wasn't made of metal. We followed the instructions on how to install it in a metal door to a T, even adding extra silicone to create a thicker barrier between the metal door and cat door. Yet even with doing all that, the pet tags it uses are useless, I can barely trigger the flap to unlock by myself physically holding the tag to the specified area (and when it did trigger it was inconsistent). I was completely unable to get the cats to trigger it while it was on their collars. And unfortunately there is no way for the unit to be used without these tags. So we pretty much spent over $200 total on this set up for it to now be completely useless. After reading the return policy, it's not likely we'd be able to return it after installing it either. I also wouldn't recommend this for skiddish cats, the sound of the flap unlocking once triggered by the color is loud and abrupt and my timid kitty wanted no parts of being anywhere near the door. However, it didn't seem to scare my other cats too badly. Another downfall to the unit is that the flap will not unlock (even if the magnetic tag is triggering it) until the cat pushes it's head forcefully into the flap, which at that point it would [loudly] unlock. The concept of the unit is great and it has some cool, unique features (which is why i gave it 2 stars). But even if these tags worked, i still feel this unit has a lot of downfalls and I would not recommend buying it.