MP3-138 plug and play, with Scan FM radio, powered by AAA battery, USB flash drive, software-free to fast download MP3 song from PC, simply use window, five preset EQ for MP3: Rock, Jazz, Classic, Pop,Standrad, plya time up to 8-10 hrs, storage capacity:32M/64M/128M bytes small size: 100 x 30mm x 16mm strong anti-shock capability, complete electronic interface, strong anti-EM wave capability, high data retention capability, possible read/write cycles> 100,000 times, retention period> 10 years.