We are offering sports mp3 headphone. 1, high speed usb 2.0 (fs) interface 2, micro sd card slot capacity expansion:maxmum surporting to 8g 3, compatible operating systems:win me/2000/xp/mac os 9.2.2 or any other super versions 4, colors available:yellow, green, red, black, blue, etc 5, audio format:mp3/wma/amv 6, built in 150mah rechargeable li-ion battery act as usb flash drive voltage: 3.7v usb power keys: volume+/-, play, pause, previous and next led indication light speaker power: 2 x 10mw 16 steps volume adjustment come with accessories: mini earphone, usb cable, charger, user manual