This audio mixer supports 4 input to 1 output, and each channel can be individually controled by the potentiometer. It can directly drive the headphones or connect the amplifier which interface is 3.5mm stereo socket. If you are interested in this product, come and have a try, it will not let you down. Features: This audio mixer supports 4 input to 1 output, and each channel can be individually controled by the potentiometer. It can directly drive the headphones or connect the amplifier which interface is 3.5mm stereo socket. Portable Size: The small size of this tool is very convenient for everyday use, and it will not taking up too much storage space. The magnification is about 2 times, which can meet your most needs. The cover is made of metal material, superior wear and corrosion resistant, not easy to rust and can provide a long service time. Specifications: Material: metal Input&output: 3.5mm Magnification: about 2 times Quiescent current: about 15 mAh Item size: 110 * 60 * 27mm / 4.3 * 2.4 * 1.1in Item weight: 117g / 4.1ounce Package size: 130 * 110 * 40mm / 5.1 * 4.3 * 1.6in Package weight: 150g / 5.3ounce Packing List: 1 * Audio Mixer