Ultimate Brass VITAL BOND Bore: 28.5 This model was supervised by Zachary Bond, bass trombone player for the Malaysian Philharmonic Orchestra. Compared to other Bond signature models, this is a slightly lightweight model with a playing feel similar to a Bach mouthpiece, but with a moderate resistance, offering excellent operability. It may be characterized by its warm and transparent sound. I have used it for about a year, and there are no noticeable scratches.