"Microsoft Wireless Optical Desktop Elite gives you two essentials – keyboard and mouse – in a single package. You get it all – top performance, sleek design, and state-of-the-art features – including Microsoft's revolutionary Tilt Wheel Technology. Together, it adds up to the ultimate in features and functionality. Optical Technology - High performance optical technology – no mouse ball - Optical sensor delivers greater accuracy and control. Tilt Wheel Technology Microsoft Wireless Optical Desktop Elite has Tilt Wheel Technology on both the keyboard and mouse to make scrolling easier, smoother, and faster than ever: - Side-to-side scrolling – now you can scroll horizontally as well as vertically. - Smooth scrolling – feel the unique wheel glide smoothly as you scroll through documents and web pages. - Enhanced Accelerated scrolling – Leap even farther and faster through your documents. Wireless Freedom with Longer Battery Life! - No cords or recharging station. The keyboard and mouse work within 6 feet of the receiver, even if your computer is out of sight (receiver included). - Longer battery life – many users average more than 6 months battery life! - 27 MHz wireless technology just got smarter. The Microsoft Smart Receiver notifies you of interference from other wireless devices and leads you through steps to reduce that interference. It even sends a message when the battery is low."