The noise isolator is designed to completely eliminate the annoying humming / buzzing noise caused by ground loops. It improves the audio, music, speech quality with ultra simple operation, just plug it and go, no external power or battery required. Ultra compact size, exquisite workmanship and delicate quality, elegant shape, easy to be carried anywhere for multiple use. Method to judge whether the noise is caused by ground loops: 1. Connect the earphone to the 3.5mm interface of car’s MP3 and navigation. If there is no noise from the headset, it can be confirmed that the noise of the vehicle is caused by ground loops. 2. Connect the mobile phone or MP3 player to the car AUX ( the phone and MP3 should not be connected to any power source in the car), and then play music on your phone. If there is no noise, it can be confirmed that the previous noise is caused by ground loops. 3. Computer, power amplifier, audio, CD: connect a passive earphone to the computer, and connect a mobile phone to the amplifier and audio. If there is no noise between the two, it can be confirmed that the previous noise is caused by ground loops. Specification: Type: Ground Loop Noise Isolator Material: ABS Color: Black Application: Motorcar horn / home sound system Audio Interface: 3.5mm Isolator Size: Approx. 6*2*2cm/2.4*0.8*0.8inch Weight: Approx. 34g / 1.2oz Package List: 1 * Ground Loop Noise Isolator 1 * 3.5mm Audio Cable Note: Only a ground loop noise isolator and a cable included, no other stuff.