Trumpet mouthpiece. ■Manufacturer: YAMAHA Yamaha ■Model Number: Signature Model Eric Aubier Model ■Finish: Silver-plated ■Outer Box: Yes ■Condition: Near new condition, with only a few test plays. Features a rich, core sound. The rim is similar to 16C4, making it an all-around model. Rim Inner Diameter: 17.03mm Throat Diameter: 3.80mm I think it's equivalent to Bach 1-1/2C.