The XO Professional Series F Attachment Trombones include hand-crafted bells, brass outer slide with nickel silver crook, and three interchangeable leadpipes as well as an available Thru-Flo valve. All models also include a professional classic-style case. This symphonic .547" bore trombone series truly exudes the word "professional". Loaded with special features and different player options, the 1236 commands a feel and playability that raises the benchmark to a new level of performance. This trombone begins with a beautifully engraved, handcrafted rose brass 8.5" bell with soldered bell flare wire for increased resonance and sustain. The hand slide boasts brass outer slide tubes with a round nickel silver crook for unimpeded air flow. Chromed inner slides ensure fluid yet articulate operation. This instrument has the very free blowing .563" bore Thru-Flo valve section. Two brass and one sterling silver interchangeable mouthpipes allow the artist to custom tailor the instrument's air column for the desired response.