This is the "ALESSI 5B" trombone and euphonium large shank mouthpiece from the American instrument maker "GRIEGO." Inner Diameter: 26.02mm Throat Diameter: 7.19mm Cup Depth: Medium It's the same size as the current Artist Model 5B. It has a similar feel to a Bach 4G with a shallower cup. It was very easy to play and produced a brilliant sound. The gold plating felt comfortable on the mouth. There are some scratches on the throat from use, but otherwise, it's in relatively good condition. Feel free to ask any questions in the comments.