This is the newer, blue unit. It is a 4-track digital recorder. It has 8 virtual tracks per track for a total of 32 tracks. It records to SmartMedia cards. It has built in effects for bass, guitar, microphones. It has a built in condenser microphone so that you can use it to quickly get song ideas down. It has built in rhythm patterns, so you don't need an external drum machine. It operates on both AC and battery power. You could use it as a portable practice tool, like a Pandora. It has a slow down function, so that you could slow down a song that you are trying to learn and play back along with it. It has a USB port so that you can transfer files to a computer for further editing or to burn to CD's. It records to MP2 format, but there is a free utility that you can download from the Korg website that allows you to manage your PXR4 files on your PC and also converts the MP2 files to .wav files so you can transfer them to DAW software like Cakewalk, Cubase, Audacity, etc for additional editing and mastering or burn the songs to CD using Windows Media, Pyro, Nero, etc. I have all of the original packaging, including carrying case, AC adapter, 16mb SmartMedia card and manual. A great way to get into digital recording for $175 shipped. I take PayPal or money order. Please PM me with any interest.