You can adjust frequency. Just gently rotate button of the controller, and you can also control the sound with different frequencies, so that song sounds different, the heavy bass is deeping and it is very convenient to use. Installation is usually very simple, with detailed instructions, suitable for enthusiasts to modify, but also by professional to install. Improve the bass of the sound, so that car owners can enjoy a better music while driving and increase driving pleasure. Optimized your driving sound track during commutes, or daily errands while maintaining control over bass intensity from driver seat. Suitable for head units, home sound systems, and amplifiers requiring control.