Maybe I'm way behind the times, but I had never heard of these little wonders until recently and now I can't seem to get my mind off of them. According to the description and the information I was able to find elsewhere online, they typically grow to a height of 8-10 feet and never branch-out, thereby maintaining their slim look. They are typically about 2 feet wide. They are hardy trees as well as early producers and the fruit is full-sized which was a concern I had. Generally, they will produce fruit for around 20 years!
The site linked below is selling them as a pair in order to ensure proper pollination.