This midi pedal has not only a midi-output, but also 2 inputs, which allow you to hook up 2 different keyboards which will be merged with the pedal-data to the midi-output connector. Although the Hammond XPK-200 midi-pedal is usable with any keyboard, the combination with XK-1 or XK-3 (or older models XM-1, XB-1, XB-2, XK-2 or XE-1) makes for a real great setup.