Earphone:1) Impedance: 2 x 8, 2 x 16, 2 x 32, 2 x 402) Sensitivity: 110?dB3) Frequency range: 20 - 20,000Hz4) Rated power: 2 x 100mWMicrophone1) Impedance: 1,800, 100, 2002) Sensitivity: -48?dB3) Directivity: omnidirectional4) Frequency response: 30 - 16,000Hz producing area:China payment:T/T in advance supplying capacity:50000/month