I bought the trackball because I have to work properly in a small space and a variety of terrains and also a scroll function need. The trackball was purchased from another supplier because Amazon Marketplace seller not sent to Austria. The ball runs quietly and is perfectly done, in my view, may be included in your model just a production error. The scroll function is perfect! I use the ball in the following ways: Thumb makes the left mouse button. Forefinger the ball. Middle finger is the scroll wheel which hardly has resistance and thus "shoot" for larger scroll stretching a piece of leaves. Pinky makes the right mouse button.
The only complaint: the buttons could be a bit softer and more precise will react, the pressure point is somewhat inaccurate. -> Only 4 ****
