Fangrui Product Details When You Have Multiple Audio Devices That Need To Share The Audio Or Power Amplifier, Several Devices Can Be Connected At The Same Time, Which Output Is Used, Which Is Convenient And Practical Without Switching. One 3.5mm Stereo Interface, Four Interfaces, One Ra Output, And One 3.5mm Headphone Output; Several Audio Sources Can Be Connected At The Same Time, Without Affecting Each Other, And Can Be Mixed Or Output Separately; Power Supply Dc 5-19v, It Is To Use Linear Power Supply, Switching Power Supply Is Easy To Produce ; With Gain, The Output Port Is About 2 Times, And The Headphone Port Is About 4 Times. Color: Black Material: Metal Package Contents: 1 X Headphone Amplifier Mixer 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.