Designed to fit flugelhorn or alto trombone, large or small belled. The black Wick practice mutes are known for their excellence. They blow more freely than most practice mutes yet dampen sound very well (the usual trade-off). And, they have very good intonation. Although every practice mute is a compromise, this one achieves great marks in all three categories. Note: We have received word this model might not fit Benge flugelhorns. -cdp