“The pedal features a simple design with only one switch controlling the color, and one knob controlling the rate. The two color settings switch between a more dry sounding phaser and a wet-bubbly sound. You can get anything from dry sweeping phasing, to fast wet phasing that sounds like you are playing underwater.”
Note in the additional picture, that the switch is a small, thin style switch as opposed to the larger switch as shown in the first photo. I’m guessing the smaller switch appeared on later versions.
More information here: