This is a trombone/euphonium mouthpiece for a Yacht Car. 5G Inner Diameter: Approximately 25.5mm Throat: Approximately 7.00mm Quoted from the manufacturer's website: This mouthpiece has been carefully selected and customized based on American-made mouthpieces from the 70s and 80s, which are in high demand in Japan. It's an all-around mouthpiece suitable for beginners to advanced players, regardless of genre. I purchased it but have only attached it to an instrument a few times, so it's in like-new condition with no scratches. It's suitable for American-made instruments, and how about trying it with the recently popular German-made American-style instruments? (Such as Kühnl & Hoyer and Jürgen Voigt) Retail price: 15,840 yen - 19,800 yen