I have settled around a rim size of 1 1/4 C, which is about a Yahama 17B4 equivalent. The Mark Gould, Tom Hooten, Yahama 17B4, Bach 1 1/4 C, Thein 1 1/4 CFF: should all fall within this same camp. Compared to the Tom Hooten model, this mouthpiece feels less comfortable and I am not able to get as much color out of it and intonation is not as good. There are such minor differences between all these mouthpieces, so it really comes down to just trying them out and seeing if it fits you - in terms of slight differences in rim width, rim high point, bite, throat, and taper. I only tested this on a Yahama Bb 9335V -- so perhaps it would have been better suited on a C trumpet.