This is a BEST BRASS Groove Series horn mouthpiece (7C). I usually use their 5C model, and I bought this for different situations, but I ended up not using it much, so I'm selling it. The rough texture inside the cup and the groove finish provide a comfortable playing experience. The shank is American shank. It fits Yamaha, Holton, Conn, Hans Hoyer, Wenzel Meinl, etc. It has been treated with GAT. I had it done when I couldn't practice due to the pandemic, so it's difficult to explain how effective it was. There is a dent on the shank, and there is a distortion about the size of a hair. If you are concerned, you may want to have it repaired. There is no box. This is a used item, so returns are not accepted. If you have a desired price, please comment. The following is quoted from the manufacturer's website: To embody the "wonderful horn sound" that Best Brass envisions, the weight is designed to be light. The biggest feature is its rich resonance and a smooth playing feel like velvet. Your instrument will sound even better. Rim width: 3.650mm Rim apex balance: 41% Rim shape: Slightly round Rim bite: Sharp Rim inner diameter: 17.200mm Cup depth: Medium Throat diameter: #16 (4.50mm) Backbore: HR-ML Other compatible models: Bach 11 Retail price: ¥27,500 A model with a slightly smaller rim inner diameter than the HR-5C. Since the other specifications are the same as the HR-5C, it has a rich sound and makes it easy to play in the high register. It can be used with both large and small bell horns. Thank you.