Thank you for viewing. This is a BEST BRASS horn mouthpiece. It has an inner diameter of 17.8mm, a throat of 4.7mm, and is a slightly deep mouthpiece with an American shank and gold plating. I used this in high school, and there are scratches on the shank, but I don't see any dents. Because the storage environment wasn't good, there are stains that won't come off even if I wipe them. If you don't mind the appearance, please consider it.