ScalerDroid is a SCALE TUNE application designed for Korg PA2X, PA3X, PA3XLE, PA800, PA900, PA600, Pa300 models.(For PA4X,Pa700,PA900 coming soon)Note: It is displayed correctly on 4.7" and up-size screens.for use ;You must set on keyboardGLOBAL -> MIDIFilters -> Midi IN 1 ->OffMIDI IN CH1 -> Upper1MIDI IN CH2 -> Upper2MIDI IN CH3 -> Upper3