With the exception of the “junior” mouthpieces, Nos. 30E and 32E, Bach tuba mouthpieces can be used equally well on BBb and Eb tuba. There is no good
reason for making mouthpieces for Eb tuba any smaller or shallower, because a player using an Eb tuba actually transposes a fourth and uses the instrument in the lower register, for which a larger-sized mouthpiece is to be given preference. Nos. 7, 18, 24W and 24AW have larger backbores.