This series offers two different exterior angle of the beak: Traditional and «Profile 88». Vandoren has developed the 13 series mouthpiece specifically for American clarinetists using A440 pitch. The time-proven standard for professional musicians. Quality and tradition. Features: Opening: 1/100 mm 106.5 Facing length: Medium Short Instrument: Bb clarinet Series: Traditional clarinet mouthpieces CM4018 (Single Mouthpiece) 13 Series with Profile 88 beak CM3018 (Single Mouthpiece) Profile 88 beak CM301 (Single Mouthpiece) Traditional Beak