This is a 4/4 BBb tuba with four rotary valves made in Germany by B&S and approved by Robert Tucci and many other players worldwide.
Compared to the popular Miraphone 186 tuba, this B&S has a slightly smaller valve bore (.748" vs. 772") but its open bugle is a bit larger. The vertical tuning slide, open 3-loop body and wide bell throat give this tuba a more broad and round tone like a classic US style instrument, but it still has the control of the standard bore and the crisp feel of rotary valves. Size: 494<186<GR51<Alex 163<191.