Features: Gently rotate the control knob to adjust frequency levels. Different frequencies allow customization of audio output for enhanced sound performance. Connect the RCA output of this controller to the amplifier, and connect the car stereo output to the RCA input of this unit. Ideal for subwoofer amplifier volume control. Enables adjustment of an amplifier’s power level, stereo, equalizer, or crossover volume from the dashboard or other remote locations. Adds subwoofer level control or helps balance a multi-amplifier setup. Compact design allows for flexible mounting options, providing easy access to controls. Fine-tunes the volume of any RCA line-level signal. Simple plug-and-play RCA connections; no additional wiring required. Specifications: 4 RCA ports: 2 RCA inputs and 2 RCA outputs Level control knob Frequency Range: 150Hz - 40Hz Volume Gain Range: 0dB to -12dB Dimensions: 48 x 56 x 41mm (1.89 x 2.2 x 1.61 inches) Material: Plastic Color: As shown in image Package Contents: 1 x Controller Note: Light reflection and differences in display screens may cause slight variations between the color of the item in the photo and the actual product. Measurement error is +/- 1-3cm.