This is not really an effect, but is still a pedal. It’s a passive volume control with a single potentiometer, as you can see in the photos. Very simple, but pretty good: construction is impressive, and physical feedback is perfect. At 1,6 Kg, this pedal is no lightweight either, but this is an advantage. There’s no indication of a model number on the unit, and the models on the official site www.ernieball.com are different from this one, which I suppose is an older model: you can see that this one has both in/out jacks on the right side instead of the front side. Recent models are fitted with an additional tuner output and there are both mono and stereo models. One good thing: you can actually buy original spare parts (pots, springs and cords) for this family of pedals. Prices are on a par with build quality 
