Berkeleywind been sold many band instruments since 15 years ago.
most wind instruments are Bb , only flute is play in C. that make music teacher have difficult time to teach Flute, because all the other instruments read the same note, Bb but only C flute need to play Bb key to match with other horn. So we make this special adapter can help beginner student read the same book as other trumpet or tuba,,,
of course when you play in low key ( from D to C ) had little #. but you can pull the 3rd piece tittle out. that way can make better tone as Bb instruments.