The Greenhoe GB4 tenor trombone features an orchestral large bore design modeled in the style of the finest made classic horns of the mid to late 20th century. The GB4 has outstanding projection and free-blowing feel due to its one-piece bell with soldered rim. Subtleties and nuances abound with Greenhoe's improvements to the classic design. Features: Bell Material: Yellow BrassBell Design: One-piece Bell w/ Soldered RimBell Thickness: LTBell Size: 8.5"Bore Size: .547"Main Tuning Slide: Yellow B