Korpa 
The Volume (X) Pedal controls volume and FX parameters, featuring fully adjustable rocker tension and and a Low Friction Band-Drive for ultimate durability—all in a pedalboard-friendly housing.
The Long Story
Create incredibly smooth volume swells or control your effect pedal parameters with the DVP3 Volume (X) Pedal. Its solidly-built and ready for the road with an aluminum chassis, aggressive non-slip tread, and our patent-pending Low Friction Band-Drive for a smooth range of motion without the fear of breakage or change in feel or range. For maximum comfort and precision, the DVP3's rocker tension is fully adjustable.
When using the DVP3 as an expression pedal, you can use the internal pot to set the minimum level of the parameter you're controlling with the rocker. If you want to reverse the function of the heel-down and toe-down positions, the DVP3 has an internal switch that allows you to do so.
Along with Volume, FX and Output jacks, the DVP3 also features a convenient Tuner output for silent tuning onstage.