Thank you for viewing. This is a Jet Tone mouthpiece for trumpet. It's a vintage STUDIO MODEL B. It's designed for easy high notes. It's suitable for lead players in big bands, and horn sections because it's less tiring, making it a mouthpiece for bright and brilliant high notes. The throat has been expanded to approximately #12 (4.80mm). The edge of the shank end has been smoothly sliced. It's designed for smooth breath entry. The rim size is between Bach 10-1/2 and 12 in inner diameter. If you are interested in more detailed sizes, shapes, playing feel, or used and new mouthpieces, please search for "net brass". There is a small plating chip on the rim. There are no major scratches or dents that would interfere with playing. Please refrain from comments asking for a price reduction. Immediate purchase is OK. If you are interested in used and new mouthpieces, please search for "net brass". net-brass.com