Designed specifically for lead trumpet players, the Commercial Series mouthpieces are made for those who are looking for greater depth of sound and volume when playing in higher registers. The Commercial series starts with a Classic cup, but uses a 27 throat, a 24 backbore, and increases the outside mass. Commercial mouthpieces are only available in Shallow and Medium V shaped cups. Bach Commercial Trumpet Mouthpiece, 5S. Cup Size 5S, Cup Depth Shallow, Cup diameter 16.31mm.