With the Boss OD-20 Drive Zone Twin Pedal, COSM modeling gives you the sound of 16 classic overdrive and distortion pedals plus 6 all-new tones, while deep-level controls let you shape your own sounds. Attack Shape and Heavy Octave knobs let you profoundly impact the effect. The OD-20 stompbox has 4 user memories and line out with amp simulator that's also a headphone out. Amp control jack lets the OD-20 double as a footswitch for switching amp channels. .