WORKS PERFECTLY - This amplifier bass volume control knob is specially designed to solve the problem of the car audio main control board and subwoofer volume out of sync, so that the music achieves the ultimate effect | EXTENSION CABLE - The bass control knob connector cable is approximately 12.7 feet. It is usually installed in the free position of the driver to provide easier control of the volume | EASY to INSTALL - the bass control knob is easy to install and use by plugging the 3-pin crystal connector into the sound interface of the subwoofer and the other end into the bass control knob | HIGH QUALITY - This amplifier remote control knob adopts pure copper core cable design and high-quality insulated PVC protective wires. Which with power light to indicate the connection | 100% QUALITY GUARANTEE - All of our products to give a lifetime of service. Any problems or needs, Please feel free to contact us