This is a clarinet mouthpiece by Otto Link Tone Edge, famous for its tenor saxophone mouthpieces. The opening is a size 7. It's not listed in the catalog, so the exact size is unknown, but considering that the next narrower size, 6☆, is 0.056 inches (1.42mm), this is likely quite wide. The body is thick, and depending on the ligature, a standard B♭ clarinet ligature might be too tight. (I used an alto saxophone ligature.) It has some scratches commensurate with its age, but if you're interested in a rare item, how about it? Tone Edge model clarinet mouthpiece, size 7, made of hard rubber, with cork. - Model: Tone Edge - Material: Hard Rubber - Cork: With cork - Model: Tone Edge - Size: 7 Thank you for looking.