I've used this for about six months, and after carefully removing any minor dirt from oxidation, I will ship it. My impression after using it was that it had a clear, well-balanced, bright, and deep tone. It was versatile from low to high notes, giving the impression of a well-balanced mouthpiece. It had a moderate resistance, the sound started very well, and the thick, rounded rim provided a comfortable feel. If you have any questions or concerns, please feel free to comment, no matter what. The following is a quote from the internet: http://www.japantubacenter.com/tu_mp.htm ------------- Cup Shape: Deep and very round. Cup Diameter: 32.0mm Rim Shape: Rounded on both the inside and outside. Rim Width: 8.5mm Throat Bore: 8.35mm The PT-89 model works well with CC/BB♭ tubas and can produce a very solid, thick, and heavy sound. The cup diameter is smaller than larger mouthpieces like the PT-50 and PT-88, making it easier to use for players who find those too large. This mouthpiece is recommended for players who want to play both F and CC/BB♭ tubas with a single mouthpiece. It's a very popular mouthpiece that combines the rim of the PT-84 and the cup of the PT-90. -------------- Thank you for viewing.