I had bought two of these mice (1x for laptop, desktop 1x) after 5 months working in both the middle mouse button no longer (by clicking mouse wheel downwards).
I thought her caught wrong series, therefore twice returns from Amazon two new were needed.
After a few months the same problem with the mouse on the desktop. The mouse on the laptop I do not use so often, it works Nocht.
In short: get 4 mice, previously 3 return for defect!
Absolutely no recommendation to buy, unless you want to constantly send his mouse back.