New Metra WM-KNOB universal sound level bass knob dial with bracket. This bass controller connects in-line between your aftermarket radio or line output converter and an aftermarket amplifier through RCA cables. Controller knob gives you quick and easy access to lower the volume of the subwoofers with out lowering the sound of your stereo. This allows for mazing sound tuning or an easy way to quickly lower the subwoofer sound level. The bass knob can be flush mounted into the dash for a seamless look or can be mounted under the dash with the included mounting bracket. Comes in black for a desired finish. Compact design 1x1.5x2 at 2 0z.