This is a graphic equalizer that allows for fine-tuning of the sound range. You can freely control the sound balance with the sliders for each band, optimizing the character of instruments and amplifiers. It's perfect for guitarists and bassists who are particular about their sound. I was using this until recently, and I've performed a basic operational check. Knowledge is required for use and installation. No claims and no returns accepted. Please refer to the photos for the product's condition. This is a used item, so please refrain from bidding if you are extremely sensitive or looking for a condition like new. We will ship within 2-4 days after the bid. Management number: 58