1. Flip-up lenses that maximized protection against sun, wind and side impact. 2. Lightweight frame material offers all-day comfortable. 3. Shock proof and anti-static electricity. 4. Available flash memory size: 64MB, 128MB, 256MB, 512MB, 1GB. 5. Compatible format: MP3, WMA. 6. PC interface supported, USB2.0 protocal (Full speed). 7. Signal-to-noise ratio: 87.2dB. 8. Play function: play in order, pause, resume playing etc. 9. Continuous playing time: 5~6 hours. 10. Recharging time: 3 hours. 11. 150mAh/3.7V built-in Lithium Ion Polymer recharging battery. 12. Sound output mode: stereo. 13. Maximum input power rating: 5V DC, 150mA. 14. Audio additional feature: Auto-power off. 15. Earphone output power: 5mW+5mW, earphone impedence: 16Ω*2. 16. Normally works current: 30~35mA. 17. Voice output frequency: 20Hz ~20KHz. 18. Share same USB port for Download, Upload and Recharge. 19. Earphone fixed lever can be rotated 270 degree, and can retract and extend about 13mm. 20. Earphone can be rotated 90 degree.