3.5mm Cable Ground Loop Noise Isolator: Anti-Interference Safety Accessory for Stereo Car Audio eliminating the buzzing noise, caused by ground which happens when the audio source and the speaker use the same power source in some car speakers / home stereo systems when using the Bluetooth receiver. 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. 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 direction limited,just plug one jack as input,The other is output. It can use from both sides Audio input: stereo Frequency response: 20HZ-20KHZ Audio interface: 3.5mm Colour:black Material: ABS Size: 11x7x3cm Package Contents: 1 x Noise reduction line Only the above package content, other products are not included. Note: Light 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.