Cornet mouthpiece, Alliance 3B. This mouthpiece came with the instrument when I purchased it, but I'm selling it because the size didn't suit me. I've used it only a few times for testing. Rim inner diameter: 16.50mm Throat diameter: 4.3mm The original box and pouch are included and will be shipped together. Please refrain from purchasing if you are concerned as it has been used a few times. No returns or exchanges, please.