You don't have to be an expert or a pro to appreciate Kensington's Expert Mouse Pro, which isn't even a mouse in the traditional sense (fancy that).
It's an ergonomically intuitive trackball (think engorged, upside-down mouse) housed within a sturdy chassis. It works as a PC or MAC pointing device by rolling one's palm or fingers across the top of the orb. It affects a graciously precise and accurate interface, most likely due to its internal stainless steel bearings and rock solid, beefcake housing.
The Expert Mouse Pro has four fully-programmable mouse-buttons for traditional left-click/right-click functions and then some, plus a scroll-wheel and six more "DirectLaunch" buttons acting as customizable "hotkeys" to launch applications or perform other frequent tasks in a single stroke.
The Expert Mouse Pro is suited to most any user of any skill set; from the "professional expert" leery of developing a Repetitive Stress Disorder;
the hack journalist with absolutely no desk space in which to shove around a conventional mouse; the PC game junkie attacking such trackball classics as Centipede; and (especially) kids and tots learning their way around the computer with a large, comfortable, and easy-to-understand interface device that seems, thus far, impervious to enthusiastic smashing.