These Yamaha Standard brass mouthpieces are produced with advanced computer design and manufacturing technology for unmatched precision smooth attack and easy playability. They have an ideal weight for all-around use and available in a variety of configurations to suit every player. Compare to: TR11: Schilke 11 TR11A4: Bach 7E TR11B4: Bach 7D TR11C4: Bach 7C Giardinelli 7C TR13A4a: Schilke 13A4a TR13B4: Bach 6C TR13C4: Bach 6B TR13D4: Bach 6 TR14A4a: Schilke 14A4a Giardinelli 6S TR14B4: Bach 3C Schilke 15B TR14C4: Giardinelli 5C TR14D4: Bach 5B TR14E4: Bach 3C rim very deep cup TR15B4: Bach 2C shallower cup TR15C4: Bach 2C TR15E4: Bach 2C rim very deep cup TR16C4: Bach 1-1/2C TR16D: Bach 1-1/2C deeper cup TR16E4: Bach 1-1/2C rim very deep cup TR17B4: Bach 1-1/4C TR17C4: Bach 1C TR17D4: Bach 1C deeper cup TR18C4: Bach 1 TR5A4: Bob Reeves OES 69 TR6A4a: Schilke 6A4a TR7A4: Purviance 4 (4*D4) TR7B4: Schilke 7B4 TR8C4: Bach 10-1/2C Giardinelli 10C TR9C4: Bach 7C with smaller rim diameter