Adams A9 Bb TrumpetMany of our clients have been asking to take the classic design concept of the Martin Trumpets of the mid 20th Century and improve on the sound, intonation and slotting. The result after much prototype work is the A9 Trumpet. This trumpet comes standard with a large bore of 12 mm, but is also available in a medium large 11. 5 medium bore when ordering as a custom instrument. Specifications A9 Key: Bb Bell: 0. 50 mm yellow brass, one piece hand