The new Bach Commercial Mouthpiece is designed for everyone from the aspiring lead trumpet player, to the seasoned veteran who is looking for something to new. Two different Cup Designs, a Shallow Cup or Modified V Cup, give the flexibility to get the right feel for you. All Models come designed with a #56 Back Bore, a #27 (.144") Throat, and modified comfort rim with a fatter top. The Outside shape of the mouthpiece has elements of both the Standard Bach 351 Models and the Bach MegaTone K351 Models.