Parts selection: Parts s, With high sensitivity: High reducibility, It is full and pure compared with the same kind of sound. Circuit design: Stereo two-channel independent design, it is very suitable for car internal installation such as small space. Connection mode: Through 3.5mm headphones input and output. Main functions: The elimination of the current sound, co-ground isolation audio transformer elimination AUX earth-borne current sound, the output ground wire and the output ground wire are isolated by transformer, no common ground. Specification: This product is an audio common ground isolator, which is effective for noise caused by common ground between the audio source and the receiving device. To put it simply, common ground means that the grounding points of two electrical appliances are not at the same point. Due to the difference in grounding resistance, noise is transmitted into the electrical equipment through the ground wire, causing interference. Because the ground points of the two devices are different, common ground noise may be generated. In the car audio, there is a kind of audio interference, like a whistle sound, the frequency of this noise will change with the engine speed. Therefore, this product can only eliminate the noise and current caused by the common electric and common ground products, but cannot eliminate the noise caused by other reasons, so you need to personally confirm the source of the noise. Size Chart: Size: 50x50x15mm / 1.97x1.97x0.59inch Package Includes: 1 Piece Noise Filter Board