I purchased this for airline travel for my small Siamese cat but it was way too small, though very well built.  I purchased size S to meet airline requirements but will try a size M though possibly not all airlines will accept it.  I received it today and am trying to return it but the online return site is not cooperating and I am frustrated.

Pros: Well made and attractive.  The wheels can come off if necessary to fit under the airline seat.
Cons: Size S is too small for a small cat to curl up in.  That's small!!!