This  KLW model E1 noise cancelling microphone headset is great for customer service, call center, or just for use in the office. The ear protector adopts high quality PU leather material making it soft and comfortable to wear. The headset is circumoral and has noise insulation with anti-fatigue material to help cancel out surrounding noises that is in the room. It has USB 2.0 interface making it easy to just plug and play. The horn diameter is 30mm (about 1 ½ “) and the horn sensitivity is 110db and the speaker's impedance 32ohm with a frequency response from 20Hz to 20kHz. It has a rated output power of 41mw and a maximum output power of 84mw. The noise level is less than -78dba and the dynamic range is 78 dba with a total harmonic distortion that is less than 0.1% and the stereo crosstalk is less than -52 dba. The microphone is 6mm x5mm (about 0.24”x 1.20”) with a sensitivity that is -52db and a impedance that is less than 2.2kohm and has a frequency response from 50hz to 15khz. The wire length is 2m (about 6 ½“).