Headset Key Features: 1. Ultra noise-cancelling microphone ¡ª filters out background noise, so voice transmission is exceptionally clear. 2. Flexible boom allows the mic to be positioned for optimal comfort and voice transmission 3. Acoustic shock protection circuit 4. Adjustable headband can be adjusted 60mm 5. Flexible ear bud allows in the range of 180 degrees. 6. 330 degrees rotatable MIC boom 7. Quick-disconnect feature 8. Replaceable soft foam or soft leatherette ear pad optional 9. Unit driver: 27mm 10. Impedance 150+/-20% 11. Frequency Response 300-3K Hz 12. Distortion: Less than 1% 13. Sensitivity: 108dB 3dB/mw at 1KHz 14. Omni directional Microphone 15. Frequency response: 20-3500Hz 16. Impedance: 2.2k ohm 17. Sensitivity:-42dB 2dB 18. SNR: 55dB 19. Distortion: Less than 1% 20. Warranty: 2 years, RoHS and CE approval 21. Made in China. Paper box size:18.5*14.5*6.7cm for one unit 10 units/3kgs.