Specifications: 1) PC interface supported: USB 2) Digital formats supported: MP3/WAV/WMA 3) Signal-to-noise ratio: 87.2dB 4) Playback modes: random play 5) External hard drive function: yes 6) Sound output mode: stereo 7) Audio additional features: auto-power off 8) Earphones type: binaural 9) Mfr estimated battery life: 6 hours continuous 10) Charging time: 3 hours continually 11) Battery tape/capacity: built-in lithium-ion polymer / 3. 7V, 180mAh 12) Maximum input power rating: 5V DC,150mA 13) Voice output power: 55mW 14) Voice output frequency: 20Hz ? 20kHz 15) Earphone impendence: 16 x 2 16) Memory flash: 128MB / 256MB / 512MB / 1G (Samsung) 17) Glasses: polarized lens from an America company Polaroid 18) TR 90 flame 19) Shock proof and anti-static electricity 20) Colors available: black, silver, blue with black, brown and yellow and green and black 21) Accessories: 1 x car charger, 1 x AC adapter, 1 x user manual, 1 x disc, 1 x USB cable