This is a now-discontinued SmartMedia recorder, mixer, multi-effect device and drum/bass machine and tuner, all compacted into a single pocket-sized body.
When purchased, I recorded single acoustic guitar and vocal tracks for two songs on it, and only used it again once for its guitar effects while recording onto another device. Since then it's lived snugly in its box.
The built-in guitar effects are quite varied and impressive. I found the best way to record vocals was to create a microphone windscreen by taping a piece of tissue paper over the built-in microphone to reduce harshness and “P” popping. The drum machine sounds reminded me of a good old Alesis. This unit will work best with a SmartMedia card with more space on it than the one provided. Overall, I found the functions, features and their quality pretty impressive, given the PS-04's tiny size. I'm selling mine because my 63-year old eyes simply need the big old knobs faders and meters of the good old days. I never got completely used to cellphones either.