Schilke 20F mouthpiece for flugelhorn. Inner diameter 17,78 mm (.700 inch), 24 bore. Compares to 20 rim in diameter.The flugelhorn requires a deeper cup and larger throat than a trumpet or cornet mouthpiece. The Flugelhorn Series feature a deep V-shaped cup, large throat and backbore with a American shank for a soft, dark tone, silver plated.