The RT-44 provides great projection for larger tubas. The 44 uses a shallower cup that emphasizes brilliance and more color. The slightly larger bore compensates for the shallower cup. The fast response and flexibility of the RT-44 makes it ideal for BBb and CC tubas.
Specifications:
Cup: Inner diameter, 33mm/1.3in, medium large depth, funnel shaped
Rim: Width 7.5mm/0.295in, rounded inner and sharp outer edges
Bore: 8.4mm/0.33in