The pedal operates on high voltage, as well as the tube amplifier allowing vintage tube tone. Built in there is a switch for selection for tube rectification for warm, silky tone. Designed in 3mm aluminum, extremely solidly constructed with the tubes bumpers. The pedal uses three tubes, two of which are for gain and one as a power supply. Tubes are standard 12ax7, as well as replacement, and are interchangeable. Pedal is designed to obtain true tube sound even on simple transistor amplifiers and you can obtain tube amp with a compact design.