Schilke Heavyweight Trumpet Mouthpieces are a great choice for the player looking for a mouthpiece with more mass. The Heavyweight Series features added mass to provide a darker, focused sound with more secure slotting and increased projection at louder dynamic levels. Cup Diameter (First number in label): cups range from shallow to deep in numeric order from low to high Cup Volume (First letter in label): volume ranges from A to E from small to large - A: Small; B: Medium-Small; C: Medium (Standard); D: Medium-Large; E: Large Rim Contour (Second number in label): rims range from roundest to slightly rounded in numeric order from low to high - 1: Roundest; 2: Simi-Round; 3: Standard; 4: Semi-Flat; 5: Slightly Rounded Backbore (Last letter in label): backbores range from tight to large in alphabetical order: a: Tight; b: Straight; c: Standard; d: Slightly Curved Out; e: Large Model Diameter mm Diameter Inches Description 6A4a 15.99 .630 Small diameter mouthpiece with shallow œA cup and cushion #4 rim. 13A4a 16.76 .660 The shallow œA cup, semi-flat #4 rim and tight œa backbore creates an ideal lead mouthpiece. 13 16.89 .665 Rounder rim provides increased flexibility and quick response. œC cup offers volume for tone. 14A4a 17.09 .673 A shallow œA cup, semi-flat #4 rim and tight œa backbore for lead work. 14 17.02 .670 With a standard rim, cup and backbore, the 14 is an excellent choice for all around playing. 15A4a 17.14 .675 A larger diameter mouthpiece with our œA cup and tight œa backbore for upper register playing. 15 17.12 .674 An excellent all-around mouthpiece with standard C cup and #3 rim. 16C4 17.20 .677 A standard cup and #4 semi-flat rim for a more traditional feel. 17 17.33 .682 A standard cup and #3 rim, this model is well suited for both classical and jazz styles. 18 17.52 .690 A larger diameter mouthpiece with our standard œC cup and #3 rim. Ideal for symphonic work. 20 1...