Very good, ergonomic, vertical mouse wifi + bluetooth. It will definitely fit medium and small hands but not so much large ones, due to size.

The position of the hand / especially the thumb is closer to the Logitech mx vertical ergonomic series, slightly tilted to the left for right-handed users (handshake position but a bit more curved than the Logitech) and not to the classic Evoluent 4 (vertical thumb on the desk with a large lateral surface for the palm, almost vertical).

It remains lightweight with the battery inside without giving a feeling of a fake and cheap product. Good buttons, not in the "clicky" category, well-responsive scroll wheel although a bit noisy, very good battery consumption in Bluetooth connection but also in wireless 2.4 with USB, easy connections without interruptions with a multitude of devices tested.

Obviously, a few days of patience are required to get used to it if you have never used a vertical mouse before.

Therefore, it is definitely a decent case of an ergonomic mouse for more comfortable use at a reasonable price. However, it is not particularly compatible with large hands in my opinion.

It is a pretty good mouse for its price, it has fallen without breaking unlike the previous one that had double the price.

update
After a year and a half, the left button needs force to work