The CR78S is comparable to Bach 3 inner diameter. This shares the same rim as the CR78M with a shallow V cup design. This rim profile is a bit wider than all of the classical models, but not as wide and cushioned as the commercial models. All the inner diameter specs stay the same for each of the models, but the outer diameter increases on all of the classical models, and decreases on the commercial models. If you play a Bach size 3, and want to keep a similar inner diameter for your commercial set-up, then this is the mouthpiece for you. This mouthpiece has more resistance than the old Jet-tones providing more endurance, better projection and an easier high end. The sound is full and resonant from the very bottom of the range to the top.

CR78S: 0.6519 inner diameter measured at 0.030" 0.1410 throat 28 drill