Tenealay 2 Way Audio Mixer, 3 Point 5 Mm Un-Powered Mixer, 2 To 1 Stereo Aux 3 The X21 is a stereo two channel passive mixer for expanding a console mixer, mixing instruments, cd players, cassette players, computers etc. It requires no batteries or other power source. The unit may also be used as a 1 in 2 out stereo splitter box when all controls are turned completely clockwise 2 Stereo 3.5mm Inputs 1 Stereo 3.5mm Output Package contains: X21 audio mixer x1 Stereo 2 input / 1 output: It can connect 2 audio inputs at the same time. Each track has an independent volume adjustment knob, which can be output by headphone and speaker. The perfect way to listen to music and mix multiple sound sources incl. smart phones, tablets, computers, MP3 players, CD, etc. The unit may also be used as a 1 in 2 out stereo splitter box when all controls are turned completely clockwise Ultra-small mixer: Easy to carry and operate and mix multiple sound sources without limitation and boundary; Plug and play, no power supply required, small size, easy to place, suitable for your desktop and office. Note:This passive product does not need power supply, and there is no internal amplifier circuit compensation, so the output will be attenuated (high impedance load attenuation is small, low impedance load attenuation is large)