Better control of the flute.

The flat shape makes it easier for the player to use lip and tongue control to adjust airflow and tone. Compared with the round mouthpiece, the flat recorder mouthpiece is easier to grasp and operate, and can adjust the airflow and tone more accurately, allowing the player to better control the musical expression and playing skills of the flute. So the mouth of the recorder is flat.

The recorder is a woodwind instrument with a long history in Europe. It has been used since the Middle Ages and originated in Italy in the 15th century.