A warm and organic sounding optical tremolo. The knobs are: Rate to vary the speed of the trem, Depth for the amount of the effect, and Wave control to travel from square waveform at the minimum setting to the left, to triangle at the far right, in between you have some sine/rounded square waveform with a bit of asymmetry like an amp trem.
Demo by Guitar.com (EN)
Official Product Video (EN)