TWO1 - Professional Model. From aspiring beginners to experienced professionals, the TWO1 professional model has gained popularity with its strong tonal core. Key of Bb. Range from low Bb to high F#. All hand engraved. Yanagisawa ‘Professional’ models are free blowing, with a resonant tone, and deliver a superb performance across all musical genres. The student will develop their own unique style more easily due to both the advanced construction and ergonomic key design, and the advanced professional can be assured of both superior tone and a class-leading playing experience.