The Electro-Harmonix Micro Stereo Pulsar Tremolo Effects Pedal is everything you love about the Pulsar in a small, die-cast aluminum package. Controls: Wave shape switch: selects between the wave triangle mode and the square wave mode. Shape knob: changes the shape of the waveform that modulates the tremolo. In wave triangle mode, as the shape knob is turned from the fully counter-clockwise position to the center position, the wave starts as a rising sawtooth and becomes a triangle. From the center position to the fully clockwise position, the wave changes from a triangle to a falling sawtooth. In square wave mode, as the shape knob is turned from the fully counter-clockwise position to the center position, the wave starts as a small pulse-width wave and becomes a square-width wave. From the center position to the clockwise position, the wave changes from a square-width wave to a large pulse-width wave. Depth knob: adjusts the amount of tremolo that will be applied to your signal. Rate knob: adjusts the speed of modulation for the effect. Rate/status LED: if the effect is engaged, the LED will blink at the same rate that the effect modulates. If the LED is off, the Pulsar is in bypass mode. The footswitch engages/disengages the effect. 9V DC power jack.Small die-cast aluminum case saves valuable pedalboard space Depth, shape, and rate controls 9V battery or optional AC operation