takes is just one AA alkaline battery (included) for you to enjoy up to 75 hours of music playback. Great for long trips or vigorous workouts. Just don't hurt yourself trying to outlast that battery.Advanced D.sound technology is comprised of four components that work together to elevate your audio experience to the next level. A Digital Amplifier helps reduce distortion and also helps you achieve crystal-clear sound even at higher volume levels. The S-XBS and Digital Audio Gain Control help to improve bass response at higher volume levels and MP3 Re-Master technology allows the listener to receive outstanding sound quality from compressed music files, such as MP3 and WMA.Microsoft PlaysForSure is a marketing certification given by Microsoft to me...  (less)