BBb-Tuba, compact style, bell 47 cm, 4 valves , Model 91A (191 4V), Bell diameter 470 mm (18,504 inch), rotary valves, nickel silver trimmings, spiral spring system, Bore of valve section 21,2 mm (0,835 inch), brass body, nickel silver wreath, Material of mouthpipe nickel silver, Mouthpiece TU33, lacquered