This mouthpiece was modeled after an early Elkhart model Bach 3C with a Comfort Rim profile. They are 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.

3C: 0.6657 inner diameter measured at 0.030" 0.1440 throat 27 drill