I was afraid to ask too thumb but in fact there is absolutely no strength: there is no weight to carry and it can permanently resting on the ball. Moreover clicks the index or middle finger are independent of pointer movements: this is not the case of conventional mouse. The click and drag is very simple phone.
Apart from that I recognize a problem: sometimes the mouse freezes and does not respond well. At first I thought of fouling of the ball as I had read a comment. But clean it changed nothing. It is by turning off the mouse and the on again everything is back to normal. This happens to me about once every two days. It must be a software bug problem maybe on the radio link which is no longer good? If this does not worsen with time is quite acceptable because very binding can (sofa bed and you're off again!).
Last fault: I find too small for my large hand (glove size No. 10). So I crafted EVA foam plastic shell which enabled me to resolve some loan all problems: to give more volume, add an outwardly inclined support in the wrist and support the first two phalanges fingers to not have to remember them to avoid unwanted clicks. The result is very ugly but absolutely divine from an ergonomic point of view (see photo).
Regarding the quality and robustness of the plastic I have nothing to say. I did it once fall down on the floor. I picked it up in pieces (battery + trap + ball ...) have reconstructed and functioned without flinching. It does not need to slip rubberized part because not to lift or move with force (like a mouse). Or if just to turn it off and turn it on in the morning and evening, which is not always simple indeed. As for the return was not taken: it behaves like a turtle.
