This is a vintage graphic equalizer. It's said that just running audio through it improves the sound, and even in a flat state, it does indeed make the sound clearer and more defined. This is likely due to the 100V power supply and old op-amps. The equalizer works well and has been useful for fine-tuning sound in live performances and recordings. All sliders function without issue. There is some crackling, but it doesn't affect performance. The 62Hz knob is bent, but it still works. This listing is for the unit only.