Eliminating the buzzing noise caused by ground loops, which occurs when the audio source and the speaker use the same power source in some car speakers or home stereo systems when using the Bluetooth receiver. The working principle of this noise isolator is to achieve clear speech and music by eliminating the current noise in some car speakers or home stereo systems. Works with any portable device that has 3.5mm audio jacks for your car audio system or home stereo when grounding issues persist. Also used with a Bluetooth receiver or Bluetooth hands-free car kit in your car audio system or home stereo. Direction limited, just plug one jack as input, the other is output. It can be used from both sides. Audio input: stereo. Frequency response: 20Hz-20kHz. Audio interface: 3.5mm. Color: 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 to be slightly different from the real thing. The measurement allowed error is +/- 1-3cm.