Tilt Wheel Technology
Scroll every which way. Now you can scroll horizontally as well as vertically through documents and Web pages. The entire wheel tilts, acts as a button, and reacts smoothly to your speed. 
 
Optical Technology
Optical technology refers to the use of an optical sensor to track mouse movement, rather than the traditional use of mechanical parts. As a result, optical mouse products work on most surfaces and offer you better durability, increased speed and accuracy, and consistent performance. 
 
Ergonomic Design
Every Microsoft® hardware product has met the company’s rigorous testing requirements for unparalleled comfort and performance. Ergonomic design is important for more than productivity—how you type, point, and click can also affect your long-term health.