I know the Kanstul Company is no more. Least the last time I checked. The CG10- smallest size rim/CG Personnel V-Cup/ CG3 Cornet mouthpieces have very comfortable rims. Can be adapted with a Bach etc. Cornet M.P. to Trumpet adapter. Still be used in the Cornets. The CG Personnel Trumpet mouthpiece is the only one that has the same rim type as the Cornet CG Personnel. The Kanstul CG3 Trumpet M.P. has a different type rim than the Cornet CG3. There is another M.P. maker named Marcinkiewicz. That I believe still makes his version of the Claude Gordan mouthpieces in Trumpet/Cornet. From looking at his charts they appear to be all one rim size and on the larger size. Would have to call him for more specifics. This is late info. May later post on a new topic.