This is an envelope filter you often see, but it's an envelope phaser, not an auto-wah. It has a sound that's different from an auto-wah and matches modern music. I bought and used it because ThunderCat used it. You can get a sound close to the unique filter sound you can hear in his playing. Because it runs on 18V, the sound is thicker than MXR's Filter, and the bass doesn't get thin, so it has a strong presence even in an ensemble. This pedal is now discontinued. It has a wide range and allows for detailed settings, so it can be used for both guitar and bass. You could also get vibrato and chorus-like tones by switching modes. Operation has been confirmed. The main unit and a dedicated 18V adapter are included. It can be powered by any 18V adapter, not just the dedicated one.