Nivard and others, Wireless rodents of course don't have the gunk build-up that ball-type do. For a decade, I have been using an optical ball mouse using the thumb on my right hand. Yes, it must be cleaned periodically. Those of you with carpel-tunnel syndrome, you might consider trying the MS optical ball mouse (they are getting hard to find). This removal of the right hand movement (and only the thumb) totally removed my carpel-tunnel problem. Dale