Already after 5 minutes after I had tried the mice, one thing was certain: I'll keep both - one for work and one for home!
Granted, you have a little used to the ergonomic mouse and change. Taking it for the first time in the hand so it does not equal "love at first click." But after only a few minutes you get used to and is amazed at how relaxing the work can be now. Take the mouse completely in the hand and puts quite loose forearm flat on the tabletop. Immediately you can feel how the forearm and hand remain absolutely relaxed moment during one uses the mouse. Even after a 9 hour day I get no more problems with the arm.
This ergonomic mouse I do not want to miss - and for the price, the effect can not be beat!
As for the technical: It works just as reliable as a flat or even more expensive mouse.
The second mouse I bought is the Perixx PERIMICE-513th The only difference is that the Perixx Mouse has smooth and glossy mouse buttons, this mouse CSL TM137U not. The prices are a little different - this will cost something more. Why can not I say, since both mice are otherwise identical.
I am thrilled that one for so little money buys a reliable product that protects health.
For frequent users of computer mice this is my strong buy recommendation here.