Intermediate Series, Key: Bb, Bore: L: 13.89mm (0.547"), Bell: Gold-brass, 214.4mm (8 1/2"), Weight: Standard, Outer slide: Nickel silver, Inner slide: Nickel silver, Finish: Gold lacquer The YSL-447G features a beautiful rich tone, easy playability, and a balanced response. Their bore and bell sizes are the same as professional models, and it boasts a handcrafted assembly which you would normally expect only for a top-of-the-line trombone. The 8-1/2" bell is made of gold brass for a warm, rich sound which can fill a concert hall and the intonation is very accurate. The slide action is smooth and the quick response and comfortable playability is consistent in almost any register, at almost any dynamic. The YSL-447G offers a large orchestral bore for powerful sound projection.