Portable mp3 player series sony walkman sony b series internal memory 4 gb audio functions repeat function shuffle audio formats mp3 wma display type oled battery life audio 20 h recharge time 70 min power supplies li ion battery charge via usb connections headphone 35mm jack usb 20 functions backlight display plugplay organiser battery charging indication id3 tag colour black dimensions 84 8 x 23 6 x 15 3 mm weight 30 g