Comes with a Powerbass bass knob instead of original.Most factory stereos, even high-end systems, protect speakers by reducing subharmonic output when the volume is high. That's okay in a regular system, but this bottle neck system will handicap low-frequency performance if you want to upgrade your factory stereo with amplifiers and subwoofers. The MB1 detects the input level from a factory stereo, then adds more bass at high volume levels while keeping your bass response balanced at low volume. Now you can keep your factory stereo looking flush and its steering wheel controls intact while actually improving the bass quality and depth. The MB1 has two gold plated inputs and outputs plus it has a remote dash control for easy adjustments. The Sweep and Wide controls manage frequency ranges for extremely high precision custom built bass response. Advanced Digital Bass Restoration SystemSubwoofer Maximization Control Center100% Voltage Output EnhancementDash-Mounted Remote ControlPortable Music EnhancementWoofer Protection Circuitry Advanced Digital Bass Restoration System The MB1 MEGA BASS Digital Synthesizer contains a bass maximization circuit that perfectly reproduces and pumps low frequency back into the voltage line. Therefore, this synthesizer will enhance bass impact when using CDs, cassettes, and portable media players.DPF (DC Protection Filter) The MB1's DPF overdrive circuitry allows you to have massive, hard hitting, concrete shattering bass while protecting the speakers from DC failures, commonly found in other bass enhancement devices. Bass Expander Limiter The MB1's Bass Expander Limited circuitry allows it to enhance the bass output of any audio system while controlling damaging burps. MB1 MEGA BASS Digital Synthesizer needs to be installed in the signal path as close as possible to the source unit (between a head unit and an external amplifier)