Electro-Harmonix Pitch Fork Guitar Pitch Effect Pedal Transposes over a +/- three octave range. Three shift modes: up, down or dual. 11-position Shift knob selects the transposition interval. EXP input lets you control pitch shift or glissando via optional expression pedal. Latch and Momentary modes affect how the footswitch and EXP input behave. Comes with EHX 9.6DC-200 mA AC Adapter, can also run off a 9V battery.