B. Tilz WH-B4 mouthpiece. I selected this from several at a musical instrument store in Southern Germany. I haven't played it since trying it out, so there are no scratches on the shank, and it's practically new. It's a hard-to-find model because Tilz doesn't have it in stock and it's made to order. The rim is larger than the WH-B2, and the cup is slightly shallower than the B2 to balance it. Inner rim diameter: 33.5mm, Throat: 8.9mm #tubamouthpiece #tuba #tuba