This is the Masashi Yoshinaga model for French horn. The inner diameter and throat size are unknown, but it has a slightly small inner diameter and a stable, flat rim. It allows for sharp attacks and clear articulation. The shallow cup combined with the narrow throat diameter creates an exquisite balance, resulting in a responsive and versatile standard model. (Currently out of production) There are some minor polishing scratches, but it is in beautiful condition. Thank you very much!