Microsoft Wireless Desktop 900 (PT3-00001) Advanced Encryption Standard (AES) 128-Bit Encryption Full-size mouse provides comfortable, precise navigation Quiet-touch keys provide comfortable, responsive typing Ambidextrous design is great for use in either hand Hot keys provide easy-access to commonly used functions Customizable buttons give you access to the Windows features you use most 2 AAA and 2 AA alkaline batteries required (trial batteries included, best with Polaroid batteries)