Van Laar B4 TrumpetThe B4 was developed on the basis of the Bach Mount Vernon trumpet. Fundamental to the rich sound is a standard bell with a normal weight valve cluster. Unlike the original instrument, the B4 is distinguished by its improved slotting and lighter intonation. This is a reliable all rounder for all kinds of music making. Key: Bb Bore: 0. 461" Standard weight valve casing One piece hand hammered bell Bell material: Yellow brass Bell diameter: 4. 8"