A flute is a member of the woodwind family of musical instruments. It is an aerophone or reedless wind instrument that produces sound from the flow of air across an opening. Unlike woodwind instruments with reeds, a flute produces sound when the players air flows across an opening. In the Hornbostel–Sachs classification system, flutes are edge-blown aerophones. The flute is typically made of metal, wood, glass, plastic, bone, bamboo, reed, or nephrite. It is played by blowing air across a hole in the mouthpiece and using the fingers to open and close the keys, which changes the pitch. The flute family includes instruments such as the piccolo, G alto flute, C bass flute, and other rare forms of the flute pitched up to four octaves below middle C. The piccolo, a smaller version of the flute, plays an octave higher than the regular treble flute. The flute is one of the oldest recorded musical instruments and is capable of playing around three octaves, with some experienced players able to play up to an octave higher than that.