The optional RUX-KNOB remote bass control knob plugs right in to the MRX-M50, MRX-M100, MRX-V60, PDX-M12 and PDX-M6 mono models for quick direct subwoofer control to make bass adjustments on the fly.Compatible ModelsThe RUX-KNOB is specifically designed as the controller for use with any of the following PDX Amplifiers: MRX-M50, MRX-M100, MRX-V60, PDX-M12, and PDX-M6.From the InsideWith the RUX-KNOB, get full control over your PDX-M6 or PDX-M12 amplifier, conveniently from inside the car. With the RUX-KNOB installed inside the vehicle cabin, easily adjust the bass gain of your amp while seated inside.Multiple Amp ControlYes, there is a way to control multiple amps from just one RUX-KNOB controller – with the use of simple telephone cord adapters (which are readily available at many retailers).