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Kensington SlimBlade K72327US Trackball for $44.99 Shipped

Kensington SlimBlade K72327US USB Trackball for $44.99 shipped.  Here is a screenshot for your reference.  This multi-function ball provides the ability to navigate through music, pictures and documents using media or document view mode and has a low-profile shape. It can also control cursor and scrolling, volume, play/pause, stop, zoom in/out, and pan all with the trackball.  Most places have the Kensington SlimBlade Trackball for over $90.