This is a mouthpiece I used over 10 years ago. It's a Tilz Schmidt model 55. I believe the inner diameter was 17mm. The Schmidt model has undergone several minor changes, so I recommend this one to those looking for a mouthpiece from this era. The condition isn't great. When I bought it used, there was some stubborn dirt stuck inside the shank. I didn't mind it, but if you'd like, I can brush it with a polishing compound before sending it. (It has already been ultrasonically cleaned and brushed with a cleaner, and polished with silver polish without using a polishing compound.) Please feel free to ask any questions or request additional photos.