The triangle is now part of the orchestral percussion section. It is an instrument of indefinite pitch made from a steel bar bent into the shape of an equilateral triangle and is played by being struck with a steel beater or, for softer effects, a wooden stick. It was used occasionally in opera in the earlier 18th century, but came into its own with the Turkish music of, for example, Mozart's opera The Abduction from the Seraglio (Die Entfhrung aus dem Serail). Its appearance in Liszt's E flat Piano Concerto in 1853 caused some amusement among hostile critics. Tremolo effects are occasionally demanded.