The Sansa Shaker has a built-in speaker to enjoy music without ear buds, to play your favorite music, and listen with your friends & family.  Plus it comes with two headphone jacks so you and a friend can listen together within the privacy of your ears.  You also have the ability to play and share SD cards loaded with your favorite songs.  A SanDisk SD Memory card included.  Changing songs on the Sansa Shaker is a snap - or rather, a shake!  You can impress your friends by shaking the device to jump to the next song, or use the colorful controller bands for forward and backward changing as well to manipulate volume.  It comes with a lanyard, pre-loaded songs, and a colorful array of stickers so kids can customize their device.  One AAA battery is included which allows up to 15 hours of music life when using headphones.  Shaking action enables function to skip to next random song. Runs off of 1 AAA battery up to 15 hours.