Features: ELIMINATING NOISE: Completely eliminates hum caused by ground loops, which occurs when the audio source and speaker use the power source. OPERATING PRINCIPLE: The working principle is to achieve clear speech/music by eliminating current noise from some car speaker/stereo systems. COMPATIBLE MODELS: Works with any portable device with 3.5mm audio jacks, suitable for car audio system/stereo. also used with BT receiver in car audio system. COMPACT AND PORTABLE: Being so small and light (2.01 * 0.59 * 0.59 IN, 0.99 OZ), this little gadget does not take up much space and can be easily removed. ENJOY CRYSTAL SOUND: Ground loop isolator connects to AUX jack in car to eliminate noise. You will be able to enjoy good quality sound when you use it. Features: Black color Frequency response: 20Hz-20kHz Jack: 3.5mm Package size: 7.5 * 4 * 2cm / 2.95 * 1.57 * 0.79in Package Weight: 36 g / 1.27 oz Connection Instructions: Connect the LOOP NOISE ISOLATOR to EARTH between the speaker and the BT receiver with a dual 3.5mm audio cable or a 3.5mm to RCA audio cable as shown in the following illustration. Note: It can use both sides, without direction limitation, just plug one socket into input, the other into output. Package List: 1 * Noise Isolator 1 * 3.5mm Audio Cable