Thank you for viewing. This is a bass equalizer with a wide range of frequency adjustments. - Model: GE-7B - Brand: BOSS - Function: Bass Equalizer - Output Terminals: OUTPUT - Input Terminals: INPUT - Adjustable Frequencies: 62Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz - Level Adjustment: -15dB to +15dB I haven't been able to confirm its functionality due to a lack of testing environment. It was working approximately 20 years ago. This is a used item. Please understand that there may be hard-to-see stains, scratches, or oversights in the images. Please refrain from purchasing if you are sensitive to scratches or other imperfections. Thank you for your understanding.