AudioControl LC2i 2-Channel Line Out Converter – Stinger Off-Road – Jeep Audio And Electronics
RBC | Remote Bass Control. Dial in the perfect bass.
Amazon.com: Nobsound Auto Car Amplifier Audio Subwoofer Bass Control Knob Sub Gain Equalizer Regulator Frequency Controller RCA Line Level Adjust : Electronics
CIRMECH Universal multifunctional remote controller for USB subwoofer decoding power amplifier board with digital Bluetooth card
Car Amplifier Audio Subwoofer Bass Control Knob Sub Gain Equalizer Regulator Frequency Controller Rca Line Level Adjust - Walmart.com
Amplifier/Subwoofer Bass Volume Level Controller
Sound Ordnance™ B8PT Knob Kit Replacement remote level control for a Sound Ordnance powered subwoofer at Crutchfield
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BOSS Audio Systems SLIM10 Elite Series 10 Inch Powered Car Audio Subwoofer - Low Profile, Remote Subwoofer Control, Built In Amplifier, Under Seat, For Truck, Hook Up To Amplifier - Walmart.com
AudioControl 2-Channel Active Line Output Converter with AccuBASS and Subwoofer Control Black LC2i PRO - Best Buy