This is a Perantucci PT-89. Cup diameter: 32.0mm Rim width: 8.5mm Throat: 8.35mm Mainly used for B♭ tuba. Although the inner diameter feels small, it has depth, making it easy to control and allowing you to produce a tuba-like sound with ease. I think it would be easy to play for those who are just starting to play the tuba. I used it quite a bit, but it's still relatively clean.