If you buy one, see if they sell the replacement "discs". They will wear out and are not easy to find. I used them in my indoor enclosures with no problems except the maintenance part. I now use tall, thin cylinders. (Crystal light drink mix containers) with an aquarium air stone and a pump. Very cheap cost and I only have to ad water every other day. Mine are buried half way into the substrate and they are not going to tip over. If you can find ultra fine air stones, even better.
Maybe not better. Maybe just as good. But it's reliable and there is no fog to see everywhere.