Bach CORP. Trombone Mouthpiece 1G, Large Shank This is a used item, but it's in good condition as shown in the photos. A valuable mouthpiece with an old engraving. - Model: 1G Engraved with the old logo "VINCENT BACH CORP. 1G". This is a Bach mouthpiece for bass trombones, and it's one of the largest sizes. The size is 28.0mm, with the same rim as a Bach 5 for tenor trombones. The rim is semi-flat and slightly thin. The cup is Bach G, which is deep. It produces a dark, soft, and smooth sound. There are no major scratches or dents that would hinder performance. Thank you for viewing.