Boss OS-2 Over Drive/Distortion
The Boss OS-2 was produced due to the success of the Boss BE-5. The BE-5 featured an Overdrive/Distortion section that had great feedback due to it's versatility and unique tonal options. The OS-2 is a similar (but not identical) circuit to that, but in compact pedal form.
Produced from May 1990 until present.
The OS-2's Overdrive/Distortion control was initially created as a toggle switch however a potentiometer was used instead to cut costs. The designers loved the increase in tonal options that this created so they stuck with it.