Harmonium is a Reed Organ or a keyboard instrument that is operated by foot and produces sound through a pressure-equalizing air reservoir. The size of the reed decides the pitch but there are no pipes. The sets of reeds produce tones of various pitches. The air reservoir equalizes pressure and causes the metal reeds to screw over the metal frame slots and make them vibrate. Different tones are produced by sets of reeds. a knee-operated air valve is operated by knee and or directly from the bellows pedal which allows wind to be supplied to the reservoir there are four to five octaves in the instrument’s compass.