Miraphone 186-4U Series 4-Valve 4/4 BBb Tuba 186-4V Yellow Brass 4 Valve Nickel-Silver Slides Key: BBb Size: 4/4 Bore: .772 in. Bell: 17.7 in. Bell Position: Upright Number of Valves: 4 Valve Position: Front Valve Type: Rotary Valve Material: Brass Features: Nickel Silver Leadpipe and Wreath Case: No Mouthpiece: Miraphone TU29 Finish: Lacquer This Miraphone 186 tuba features a 770 in bore and 17 75 in