Working Principle:The working principle of this noise isolator is to achieve a clear speech, music by eliminating the current noise in some car speakers, home stereo systems.Compatible Models:Works with any portable device that has 3.5mm audio jacks, for your car audio system, home stereo, when grounding issues persist. Also used with a bluetooth receiver, bluetooth hands-free car kit in your car audio system, home stereo.COMPACT AND PORTABLE :Being so mini and light-weight (2.01x0.59x0.59 IN, 0.99 OZ), this little gadget does not take much space and can be easily taken .Audio input: stereoFrequency response: 20HZ-20KHZAudio Interface: 3.5mmColour:blackMaterial:ABSPackage Contents:2 x noise isolator2 x audio cableOnly 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.