The Numark MP103USB media player is a Rack-mountable solution for installations and DJs using CD and USB media. Whether you gig with a CD library or someone brings you a CD to play it helps to be able to play them! If youre ready to transition to performing with MP3 files or even if you already do the MP103USB USB and MP3 CD player lets you have the best of both worlds in one extremely convenient device. For DJs whose libraries live on their computer MP103USB is a perfect solution.