This is a silver-plated GRIEGO-ALESSI 5C trombone mouthpiece. Cup Inner Diameter: 26.02 Cup Depth: Medium Throat: 7.19 This is a high-quality mouthpiece for principal players and 1st chair players, offering a wide range from high to low registers. In this series, models 1A to 1F are said to be Mr. Alessi's personal models, so this is likely a model designed for a wider audience.