This is a Bach 5GO mouthpiece for large-bore trombones. This mouthpiece can also be used for large-bore euphoniums. The mouthpiece has been modified by the previous owner. The shank has been shaved for fitting and then re-plated without polishing. The shank size is not significantly different from a new one, and it remains a large bore. Also, the previous owner's engraving is present, so please refrain from purchasing if you are concerned about this. There are no noticeable scratches or stains, and I think it is generally in good condition. Please check the photos for details.