The Jupiter JTU1030M Convertible BBb Tuba is a left shoulder convertible concert and marching tuba perfect for schools on a tight budget. The JTU1030M features a .709" bore for a full sound plus a left shoulder convertible design for a comfortable marching carry position. BBb Convertible Tuba, .709 bore, lacquered brass body, left shoulder model, upright convertible, 15 bell, ABS molded case with wheels (KC-80A), weighs 17.2 lbs