Few companies know more about mouthpiece manufacture, design and physics than the Schilke Company. They make a complete line of excellent trumpet mouthpieces that work with any instrument but especially compliment their fine line of outstanding trumpets.Cup Diameter (First number in label): cups range from shallow to deep in numeric order from low to highCup 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: LargeRim 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 RoundedBackbore (Last letter in label): backbores range from tight to large in alphabetical order: a: Tight; b: Straight; c: Standard; d: Slightly Curved Out; e: LargeModelDiameter mmDiameter InchesDescription 15A4a 17.14 .675 A larger diameter mouthpiece with a shallow "A" cup and tight "a" backbore for upper register playing. #4 semi-flat rim offers comfort in upper register. 15A4 17.14 .675 Same as the 15A4a but with a larger "c" backbore for an open feel. 15B 17.12 .674 With the same diameter as the #15, this mouthpiece includes "B" style cup which produces a more brilliant sound than the standard #15 mouthpiece. 15 17.12 .674 An excellent all-around mouthpiece which offers a free blowing, clear sound. 15C4 17.14 .675 This mouthpiece is similar to the #15 but with the #4 semi-flat rim for increased endurance. 16B4 17.20 .677 Same as the #16C4 except the shallower, medium-small “B” cup offers more resistance, providing a brighter quality of sound. The 16B4 is an excellent choice for Eb trumpet when a player requires a bigger rim diameter. 16C4 17.20 .677 Like Similar to the 16 in dimensions, this mouthpiece offers our #4 semi-flat rim for a more traditional feel and increased endurance. 16 17.20 .677 With all the standard Schilke charactistics, this medium-large diameter mouthpiece produces a full, free blowing quality. 16C2 17.20 .677 This model offers the same options as the 16, but instead offers a #2 rim for increased flexibility.