A large bass trombone mouthpiece, slightly larger than a Schilke 59. • 28.65mm cup diameter. • 8.0mm (0.315") throat bore. • Silver plated. The model "B.75" is ten thousandths larger than than the Griego B1 and ten thousandths smaller than the "B.5." By adding this model, we are making a conscious effort to provide every bass trombonist with the ideal mouthpiece. Sleek "Deco" style exterior is heavier than traditional models, allowing for a darker, more focused sound. - the manufacturer