First of all I would strongly encourage looking at a different mouse this this shameful piece of plastic. I paid near [price] for this mouse when it first came out expecting dazzling results. I got nothing--it stopped working after about 2 months of normal use. I couldn't believe it!! There was no way I, myself could fix it--there's no lint jamming it, and there is no ball to check and see if it's secure. The layout of the mouse was OK-I liked the additional buttons. It is specifically designed for a right handed user as you can see. I thought I needed a new mousepad. And I got one. It continued to be jumpy just before it died. I was cleaning out my desk and just through the sorry thing into the garbage. I returned to my normal ball mouse and am skeptical of ever buying an optical again-And if I do it won't be a Microsoft!!!