Concept boring, not enough achievement studied

The concept is interesting, effective in a confined space without planne area (plane, car, ...) materials and design pouraient better. Ergonomics not well studied: distance between the thumb and not just major => tired quickly fingers. Lack of ability to adjust the sensitivity of the wheel. I wanted to give 3 stars and halves but impossible. The difference with a mouse is that you hold the pen while the mouse you wrap.