... circuit, can effectively reduce up to 85% of background noise,suitable for the long flight or in office, enjoying music ... a great confortable state. Specifications: Frequency range:20-20 000HzActive noise attenuation:100-1000Hz>10dB at 300HzSensitivity:102dBMaximum input power:500mWJack ... jackCord length:2.1mPower supply:2*AAA 1.5V batteries Noise Cancelling Stereo Headphone