Kensington Trackball Expert Mouse PRO As a spare, I purchased this on an auction site about 9 years ago, aiming for the best possible condition. Operation has been confirmed. The main unit was stored in its original box, wrapped in bubble wrap. The box has some damage, but I believe it's quite rare to find a unit and its accessories in this good condition. Judging by the wear on the ball, it's almost unused. (I myself only took it out every few years to check its operation.) Original box, PS/2 adapter, driver CD, user guide