The Vento 800 Series Model 8300 Euphonium. If you are looking for a pro style euphonium, our Vento 8300 is the one for you. It has a .570 bore for a rich, deep tone and an 11" bell for superior projection. These are the same specs as our 5200 euphonium, but this more advanced model has four valves instead of three. We furnish a deluxe case and custom matched mouthpiece to complete this great instrument.