The 1E mouthpiece has a large inner diameter which allows for great room to dance about and do lots of flexible and dynamically difficult playing. It also has a very shallow cup. I chose the mouthpiece because I needed it when carrying and dominating the brass band above the staff on the soprano cornet, but it is just too wide for the concentrated aperture I apply with my lips when playing above C3. I also use the 1C for more blending-in playing and it does the job great. The E and F series of Bach is meant to be used in the extremely high register, but the problem with the 1E is its inner diameter. It just doesn't support my embouchure enough, thus rendering it sort of useless. I will instead try out the 3E and 3F, with 16.3 mm inner diameter cups. I will not conclude with saying this is a bad mouthpiece, but if your aperture is very small and concentrated when playing high up, this large mouthpiece will do a poor job of supporting you during long sessions.