This is the 59MD, a large-bore tenor trombone mouthpiece from Laskey. It came with the Shires Q trombone I recently purchased, but I am selling it as I will not be using it. It is almost new. The inner diameter is 25.9mm and the throat is 7.14mm. It is a medium-deep, all-around model. Recommended for those who want to try various things in the 4G size. *Price negotiation is okay, but if you request it, please try commenting with an interesting or informative story related to the product or music, or your passion and enthusiasm. I will discount it based on how much it resonates with me. If you only present an amount without any comment, I will close it. (¬_¬) This is to prevent resellers.