On single-reed instruments, such as the clarinet and saxophone, the mouthpiece is that part to which the reed is attached. Its function is to provide an opening through which air enters the instrument and one end of an air chamber to be set into vibration by the interaction between the air stream and the reed. Single-reed mouthpieces are basically wedge shaped, with the reed placed against the surface closest to the player's lower lip (the "table"). The player's breath causes the reed to vibrate. The reed beats against the mouthpiece, and in turn causes the column of air inside the instrument to vibrate. The top half to three-quarters of the table is open to the inside of the mouthpiece.