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 .Compatible Models:Works with any portable device that has 3.5mm audio jacks, for your car , home stereo, when grounding issues persist.Also used with a bluetooth receiver, bluetooth hands-free car kit in your car , home stereo.Specifications:Audio input: stereoFrequency response: 20HZ-20KHZAudio Interface: 3.5mmMaterial:plasticColor:BlackPackage Contents:1 x noise filterOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.