Aluminum matte , stylish and compact design. 3.5mm AUX input and output. Support 160-300ohm impedance, exquisite and portable, easy to carry, can output excellent sound without distortion. audio, suitable for your mobile phone, MP3, MP4, laptop. Noise reduction function, enhanced dynamic distortion, perfect pure stereo effect, high-definition voice and quality optimization. Product name:Headphone amplifier Input/output port:3.5mm audio port Distortion:0.004% Signal to noise ratio: equal 120dB Load impedance:160-300ohm Frequency response:20Hz-20KHz (±3dB) Colour:Black Material:Plastic+Metal Package Contents: 1 * Headphone Amplifier 2 * Cable Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.