The EXP expression pedal allows the user to plug into the expression pedal of a wide variety of pedals. Each knob can be set to the desired value and the corresponding footswitch will active it for as long as the footswitch is held down. If the pedal is used with a pitch shifter three specific pitches may be selected then each pitch can be activated by simply holding down the momentary footswitch. The unit itself is merely an expression pedal, there are no active electronics inside. Not all pedals are standard, please include what pedal you'll be using it with when ordering to guarantee compatibility.