Soprano and contrabass instruments are very rare. Adolphe Sax and the modern maker Robb Stewart have built examples of soprano ophicleides an octave above the bass. Currently, only five contrabass ophicleides are known to exist. Three are in museums, and two are privately owned: one in Cooperstown, New York and one in Petaluma, California. Those in private hands were both made by Robb Stewart and are the only playable examples.Its long tubing bends back on itself, and it is played with a cupped mouthpiece similar to modern trombone and euphonium mouthpieces. It originally had nine keys, later expanded to as many as twelve keys, covering the large tone holes.