Features :
Playback    AAC (16 to 320 Kbps), Protected AAC (from iTunes Store), MP3 (16 to 320 Kbps), MP3 VBR, Audible (formats 2, 3, and 4), Apple Lossless, WAV, and AIFF  
Storage    4 GB  
Input    3.5-mm stereo headphone jack  
PC Connectivity    USB 2.0  
PC Compatibility    

    * Mac system requirements
          o Mac computer with USB 2.0 port  
          o Mac OS X v10.4.11 or later  
          o iTunes 8.1 or later  
          o Broadband internet access  
       
    * Windows system requirements
          o PC with USB 2.0 port  
          o Windows Vista or Windows XP Home or Professional with Service Pack 3 or later  
          o iTunes 8.1 or later  
          o Broadband internet access  
       
Battery    Built-in rechargeable lithium polymer battery  
Battery Life    Up to 10 hours when fully charged

    * Charging via USB to computer system or power adapter (sold separately)
          o 80% charged in 2 hrs; fully charged in 3 hrs.
 
Dimension (WHD)    0.7 inch (17.5 mm) x 1.8 inches (45.2 mm) x 0.3 inch (7.8 mm)  
Weight    0.38 ounce (10.7 grams)