Vertical trackball features an ergonomist-approved design that promotes proper wrist, arm & shoulder alignment to maximize comfort & minimize potential strains. 60-degree tilt angle keeps your wrist in a natural handshake position to improve wrist & forearm posture. Easy-to-use design reduces the learning curve when transitioning from a mouse to a trackball. Premium precision & speed provide more accurate & smoother cursor control, & allow you to easily switch between the dpi settings for different cursor speed control. Bluetooth technology provides a stable connection for up to three computers. Experience plug-and-play default settings or use KensingtonWorks software to set pointer & scrolling options & professionally customize nine buttons to tackle common tasks with one touch. Easy-to-clean design provides a button to eject the trackball for easy cleaning. Long battery life works for up to 18 months on the two included AA batteries.