Check the listing for details. Black Subwoofer amplifier RCA level Remote Bass Knob control with VOLTMETER. Condition: New. Listed at 79.99 USD. NEW HiFi Vector XL RCA level control for car audio amplifier. Black With red LED VOLTMETER. Voltmeter also has on off switch in case you want to turn it off. High quality components are used to insure the knob will be smooth and accurate for many years to come. High quality potentiometer is used to provide a smooth long lasting bass knob knob is easy to adjust one handed with you finger or thumb13" overall length ( including RCA cables )Input and output RCA's clearly labeled2 channels in and 2 channels out12v wires for voltmeter with pigtail connector so you can remove knob rom vehicle if needed without cutting 12v wires.Has on off switch for voltmeter 13" overall length (including cables)Dimension OF KNOB (not including cables) approx 1 3/4" x 1 3/4" X 3.75"