The Boss Harmonist PS-6 gives you four pitch-shift effects and also three-voice harmony in one unit. The effect modes are: Harmony, Pitch Shifter, and Detune, plus the Super Bend for authentic pedal-bending effects and wild three and four-octave pitch sweeps. You can also control pitch with an optional expression pedal. The harmony function is fast and simple to use, and supports a variety of interval patterns. To create three-voice harmony you choose a major or minor key, and set SHIFT to 3-VOICE.