Flutes have cylindrical holes. They are usually made of metal, often silver or nickel silver obviously there are also other materials such as gold and platinum used in their construction. Adding the keys into the flute (and changing them into the flute) allowed the player to create a wider range of notes and play more complex pieces much more simply compared to older simple flutes.
Music in Frankfurt
The city of Frankfurt is no less than other German cities in this field. There is one of the largest musical instrument makers' associations in the world in this city. The Frankfurter Musikpreis has been awarded since 1982 by the Musikmesse Frankfurt Foundation and the German National Association of Musical Instrument Manufacturers. The purpose of this International Music Award is to highlight "personalities from the world of music for outstanding achievements in the fields of interpretation, composition, musicology, education, and services to the production of music" (as described). This award is given annually and alternately to personalities from the world of music in the fields of popular music and classical music. Other major bands and singers in the city include ASP (Metal), Böhse Onkelz (Rock), La Bouche (Electronic Dance Music), Culture Beat, First Base, and Habakuk.