The unique outer shape of the Exclusive series is the result of numerous tests which had the aim of elaborating the optimum weight of the mouthpiece. It has established itself as a distinctive feature of the JK Exclusive series. The Exclusive Export Line is an enhancement of the Exclusive series. The rim diameter and shape are identical to those of the Exclusive series, allowing hassle-free switching between the series.
These mouthpieces are spectacular. I typically play sizes around a Bach 1, 1X, or 1C rim diameter. I was dissatisfied with the results I was getting on my orchestral rotary horns with my current equipment.
I own a 2B-A2 (larger than a Bach 1) that I use on my E-flat alto rotary trumpet and lower B-flat mezzo soprano rotary parts. I recently purchased a 4C-A2 (apx. a 1.25C diameter?) to try on my Rotary C and principal parts.
The C cup in the Exclusive series is supposedly a "medium" depth. Due to the cup shape and design of the throat or backbore, this might still be too large of a cup volume for what I'm looking for, but it still is an excellent option for general rotary playing or as a mouthpiece for section work. I've had some successful results on my piston C as well. Intonation is spectacular and consistent. Tone doesn't break up as easily as my standard equipment at high volumes, and response is quick at all dynamic levels. Rim shape is quite round, but very comfortable. Perfect for playing German / Austrian orchestral music!
I play rotary Bb/C trumpets in orchestras and a rotary Eb alto trumpet in chamber ensembles. I’ve been looking for something in my usual rim size (apx. Bach 1C) that was better balanced for rotary trumpets. I was looking for something that would improve intonation, give me easier access to the low register on my Eb alto, provide a more characteristic sound for my rotaries when playing German and Romantic music, and maintain articulation and playability across the range of my instruments. This really fit the bill. I don’t know all the specs, but this mouthpiece is perfect for rotary trumpets. It even sounds great on my piston C trumpet! I highly recommend this to other orchestral trumpet players.