Really liked the concept of this mouse because my trackball has a really high arch that can make the middle of my hand sore. Unfortunately I was not able to plug it into any of my computers because none of them have this kind of plug (ps2) so I am unable to try it until I get an adapter that I have been looking for (for another mouse I have with this type of plug). Should have been the description. Kind of a big unit, as wide as my palm with my fingers spread apart. Not as slender as the picture looks.Update: Sept. 2, 2012So I bought an adapter for the outdated PS2 cord that converts it to a USB port and it does not work on Vista. Downloaded several different drivers and all that happened was that it disabled my keyboard and the BSOD a couple times. May try another adapter. I so want this mouse to work , I really like the features, but Kensington does not even provide the correct driver. Hopefully a different adapter might do it. Will let you know.