Check the listing for details. Proline Universal Expression Pedal w/ Polarity Switch and Minimum Depth Knob LN. Condition: Used. Listed at 35.19 USD. The Proline PXP10 Universal Expression Pedal is designed to control volume, vibrato or any other continuous controller parameter you have available to your keyboard or effects setup. Its Range Knob limits the sweep of the pedal, keeping effect changes to a usable area. The PXP10's switchable polarity allows compatibility with nearly all devices with a 1/4" sustain jack—Yamaha, Roland, KORG, Williams and much more. A rugged-build quality and tough chassis ensures reliable usage for years, while its thick-coated rubber bottom mitigates "pedal creep" on the floor. The Proline PXP10 is also an ideal add-on for guitarist pedalboards with expression pedal effects options. Includes a top-quality 6' cable with 1/4" plug.