1)Speaker: 40mm ND 2)Impedance: 32ohms +/- 10% 3)Frequency range 20-20,000Hz 4)Sensitivity: 105dB at 1kHz 5)Noise reduction level: -15dB +/- 3dB 6)Operated by 2 x AAA batteries (not included) 7)Jack: SP-02 single 3.5mm stereo plug