A woodwind instrument of the clarinet family. It is a transposing instrument pitched in the key of E♭, although instruments in F (and in the 19th century, E) have been made. In size it lies between the soprano clarinet and the bass clarinet, to which it bears a greater resemblance in that it typically has a straight body (made of grenadilla or other wood, hard rubber or plastic), but a curved neck and bell made of metal. All-metal alto clarinets also exist.