Kensington SlimBlade Trackball Mouse with Bluetooth Wireless (Graphite) K72281US Full-featured laser mouse allows you to navigate through your documents with superior precision Unique Scroll Ball provides easy and intuitive 360-degree scrolling Trackball mode gives you cursor control in tight spaces and on any surface Bluetooth wireless technology for an instant connection  leave your USB ports available for other devices Fuel gauge indicator lets you know when it's time to change your batteries