Very good quality / price ratio for an ergonomic mouse

My first ergonomic mouse and I'm very happy.
The mouse is well made and easy to learn, very ergonomic.
The buttons fall well for a small hand like mine.
It is fast enough for a casual player like me.
What is a little confusing is that game, I find it more accurate than a desktop mouse with its closest form of a pistol grip; while in office, I lose precision when to perform the manipulation of images.
Point slightly negative: it is not accompanied by any driver. And so to use all the buttons, you must download software and more like X-Mouse Button.