I used to play on Yamaha 16E4, but for me the rim was not perfect, then on Breslmair E44 lower part, but the throat was too big (4mm). With this lower part attached to my Breslmair rim I got a very nice warm sound in every register on the Ricco Kühn C trumpet, and also easy to play. It gives the feeling of the Yamaha 15e4/16e4 with the 3.88mm throat, but you can use with any rim what is good for you.