This is a Yamaha cornet mouthpiece. (From the Yamaha website below) ・Inner rim diameter (mm): 16.46 ・Throat diameter (mm): 4.20 ・Features: Standard model for British style cornets. Offers flexibility for technical and varied performances. It's practically unused, only test-blown in a shop. The item will be wrapped in bubble wrap and shipped via Yu-packet Post Mini. Trumpet Cornet Mouthpiece