The concertina employs “double action,” each note being given by a pair of reeds, one to sound on the press of the bellows, the other on the draw. In the original and most common model, the chromatic scale is divided between the two hands; in some later models, such as the duet-system concertina, a chromatic scale is provided for each hand. The compass extends four octaves upward from the G below middle C. After the great days of the 19th-century concertina virtuoso, the instrument was gradually superseded from about 1910 by the accordion.