Altec Lansing inMotion iMmini Portable Audio System for iPod Mini Crystal-clear sound - from four custom-designed neodymium Micro Drivers (2 x 25mm and 2 x 18mm) Surprisingly deep bass - Revolutionary MaxxBass technology creates quality bass without a subwoofer Built-in Docking Station - provides same synchronization, data transfer, and recharging options as the iPod dock (cable not included) Extra long battery life - Highly efficient Class D amplifier delivers more than 24 hours of continuous playback with four AA batteries (not included) Auto Shut-Down