Description: Fits Places: The headphone amplifier is very suitable to be used at recording studio, performing stage and etc. 4 Channel: The volume control is designed with 4 channel that can be used to connect 4 headphones at the same time. Separate Control: Each channel can be controlled by separate button, which is convenient to use. Better Sound Effect: The volume control features good low noise ability, which can give you a better listening experience. Convenience: Within the package there is one DC 12V power connector, which is convenient for us to use. Specification: Material: Metal. Color: Black. Size: Approx. 10.5x5.5x4.5cm/4.13x2.17x1.77inch. Input: Line In(O IN). Output: Line Out(O OUT). Battery: No. Headphone Resistance: 65-80 Ohm. Note: There might be a few color distortions due to different computer resolutions. There might be a slight error due to different hand measurements. Package Includes: 1 Piece Headphone Amplifier(with 1 Piece Power Connector, 1 Piece English Manual).