Jupiter JTU1005MS Marching Tuba (Silver-Plated)The Jupiter JTU1005MS Convertible 3 4 BBb Tuba is a left shoulder convertible marching concert tuba and is the first choice for both concert and marching bands. Featuring a . 661 inch bore, it delivers excellent tone and response in a compact 3 4 size, with an enhanced center of gravity and balance for a comfortable playing experience, especially during marching. The unique annealing process increases the timbre and resonance to enhance performance