Operation confirmed. Includes only the main unit. Purchased new from this site about six months ago. This is a buffer/clean booster that uses a transformer. I used it with a bass, and it improved the clarity of the sound, making it more articulate. It gave a smoother sound to finger noise and fret noise, and improved the feel of playing. I haven't tried it, but I understand it can also be used with a guitar. Feel free to ask any questions in the comments! Guitar effects pedal Bass effects pedal Clean booster Transformer Buffer