The name 'glockenspiel' literally translates from German as 'bell play.' Originally, the instrument actually consisted of a set of small tuned bells. However, in the 17th and 18th centuries, the bells were replaced by a set of tuned steel bars, which were much lighter, easier to manufacture, and had a more focused, piercing tone. This modern version is played with hard mallets made of plastic or metal to highlight its brilliant, high-frequency overtones. Because of its extremely high pitch, the glockenspiel is a transposing instrument; the music is written two octaves lower than it actually sounds to keep it on the standard musical staff. It is often confused with the xylophone, but the key difference is the material: the glockenspiel uses metal bars, while the xylophone uses wooden bars. Its sound is iconic in orchestral music, such as in Mozart's 'The Magic Flute.'