Vertical trackball features an ergonomist-approved design that promotes proper wrist, arm and shoulder alignment to maximize comfort and minimize potential strains. 60-degree tilt angle keeps your wrist in a natural handshake position to improve wrist and forearm posture. Easy-to-use design reduces the learning curve when transitioning from a mouse to a trackball. Premium precision and speed provide more accurate and smooth cursor control, and 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 and scrolling options and 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.