no way to know if your to far onto the cylinder or if you need to leave a gap. It would be better to have the app just pick random settings and you read it. I know how to read one and with this I was always out .005 or so. So will unistall it and move on. Nice idea but a person need to know how or why its wrong so there is no real learning here and you cannot go back and see the reading.
Its helpful to practice the calliper measuring techniques... It helped me a lot before my practical exams..!
I really liked this as a way to learn reading a calliper, but it would be much better if the tool could "touch" the piece. Like a real one!