This trackball we have worried for a colleague who for years has major problems in the shoulder and thus can operate a normal optical mouse to significant restrictions and pain. After a certain period of acclimatization it is best in order to right. The keys are individually programmable, the trackball speed can be adjusted. The operation of the cursor takes place with the palm on the trackball. My colleague has placed on the lower left button of the trackball, the left mouse button, which they operated with the thumb. The function of the right mouse button is now on the top left and is operated with the index finger. I would recommend this trackball at any time further, especially in those cases in which already hurts the tendon sheath. Just buy it !!!