There are various types of Harmonium for use in the various commercial and personal uses. Also called Reed Organ, is a free-reed keyboard instrument that produces sound when wind sent by foot-operated bellows through a pressure-equalizing air reservoir causes metal reeds screwed over slots in metal frames to vibrate through the frames with close tolerance. There are no pipes; pitch is determined by the size of the reed. Harmonium is a keyboard instrument that is a lot like an organ. It makes sound by blowing air through reeds, which are tuned to different pitches to make musical notes.