The Jupiter 1236L Tribune XO Series Professional Trombone is designed for optimum performance and response to meet the needs of the player with a .547-inch bore with a .563-inch bore throughout the F Attachment section for a free-blowing instrument with a full sound. The 1236L Series also features an 8.5-inch one-piece hand-hammered bell for outstanding projection plus a nickel silver slide crook for increased response.