The Schilke Trombone Bass Trombone MouthpiecesIdentification LevelsNumbers 40 through 53 for tenor trombone baritone and euphonium. The numbers 57 through 60 are for the Bass tromboneNumbering SystemWhen a Schilke mouthpiece has a standard backbore, rim and cup, only the cup diameter (first number) is shown on the mouthpiece. In the example above only the 9 is necessary to identify the mouthpiece because the C is the standard cup volume, 3 is the standard rim, and C is the standard backbore. Whenever measurements differ from the standard sizes the alterations are shown on the mouthpiece.CUP DIAMETER (First number in label)Most trumpet and cornet mouthpieces have a cap diameter that falls between .600 and .725. Numbers 1 to 25 in the Schilke system represent sections of .005 each between these two measurements. Cup diameters for mouthpieces other than trumpet and cornet are relative to each other with the smallest numbers representing the smallest diameters.CUP VOLUME (First letter in label)In general the deep cup mouthpieces produce the darkest sounds. In reverse the shallow cup mouthpieces produce the brightest sounds and a