1. Optical Tracking Performance Legendary accuracy delivered from an optical engine that produces 9000 Frames per Second, Maximum Speed of 54+ Inches per Second, and Maximum Acceleration of 25Gs combined with Microsoft's Intelligent Tracking System with a centered optical port. 2. Ergonomic Design Button placement for improved sensitivity and soft touch materials for a sure grip. 3. Five Customizable Buttons Get quick access to the media, programs, and files you use most often. 4. Scroll Wheel with Detents A specially designed scroll wheel with detents enables more accurate scrolling through documents, spreadsheets, or video games. 5. Improved Slick Feet For smooth movements across a variety of surfaces.