Boss TR-2 Tremolo Guitar Effects Pedal - fully tested, excellent operating condition and sounds great. Some very minor cosmetic wear from normal use. Optional power supply not included, runs on batteries. Classic vintage Tremolo the way it should be! The Boss TR2 Tremolo is designed to provide guitarists with classic tremolo effects in an easy-to-use compact pedal. Dedicated "Wave," "Rate," and "Depth" knobs provide a multitude of effect possibilities. Key Features Built-in Wave knob offers the ability to alter the LFO waveform from triangle to square, allowing a wider range of tremolo variations. LFO waveform has asymmetric duty ratio, providing control over tremolo phasing. Rate knob is a sweepable, high speed LFO control, allowing fuller control over tremolo speed.