The manufacturer claims that this is the most energy efficient electronic pet door on the market, and I can believe it. There are multiple elements that are sealing out the cold weather, and I actually think this door is more energy efficient than the door it was installed in. We have two medium sized dogs, and both are too big to use this door, however. This is not the door's fault, and my rating respects the fact that the door will surely work very well for small dogs. There are only two issues that potential users need to know about.
1. Make sure your dog is small enough to make use of the door. The picture in the add shows a large dog using what appears to be a medium sized door. This convinced me that our two large dogs would be happy using it too. Not true. They are scared of it, and they really dont fit through it well. Get one size larger unless you are sure your dog will fit.
2. It is possible for a dog to get stuck outside if the battery drops too low in voltage while the dog is outside. The door opens electrically, and so the owner needs to make sure the battery is kept charged.
The above issues are true for any dog door that is electric, however, and my five stars are well deserved. This is I believe the most sophisticated and best insulated dog automatic door on the market.