Bach trombone mouthpiece 12C. According to my information, the inner rim diameter is 24.5mm, making it a first choice for big bands. However, it may be quite old, and I can't tell for sure. It's a used item, so there are some minor scratches, but it looks to be in good condition at first glance. There are many shallow scratches on the rim surface, but none are particularly noticeable, and I couldn't capture them in a photo. I don't think you'd feel them with your lips either. The inside of the rim cup is clean, and I don't feel any roughness when I touch it with my fingertips. The only drawback is that the tip of the shank is slightly deformed. In the last photo, the area around 10 o'clock (as on a clock face) is not perfectly round, but flattened in one spot, likely due to a drop. However, I don't think it will affect playing, and a repair shop should be able to fix it without any problems. Please check the photos for the overall condition. There is no box. I am also listing Yamaha's old model "46" and the current model "46C2" at the same time. These mouthpieces have the same class of inner rim diameter as this one, but this one has the smallest inner rim diameter and a shallower cup, although the difference is very slight. Also, what's clearly different compared to Yamaha is the outer diameter of the rim. I was convinced when I compared them again. Bach's outer diameter is smaller even though the inner diameter is almost the same, meaning the rim is rounder. No wonder Bach mouthpieces offer a wider range of expression but are also more tiring and less comfortable for the player (lol). If you'd like to purchase them all together, I can at least reduce the shipping cost, so please let me know in the comments.