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. Inline volume and mute function 8. Quick-disconnect feature 9. Replaceable soft foam or soft leatherette ear pad optional 10. Unit driver: 27mm 11. Impedance 150 +/-20% 12. Frequency Response 300-3K Hz 13. Distortion: Less than 1% 14. Sensitivity: 108dB 3dB/mw at 1KHz 15. Omni directional Microphone 16. Frequency response: 20-3000Hz 17. Impedance: 2.2k ohm 18. Sensitivity:-42dB 2dB 19. SNR: 55dB 20. Distortion: Less than 1% 21. Warranty: 2 years, RoHS and CE approval. Paper box size:18.5*14.5*6.7cm for one unit 10 unit/4kgs.