This is a Denis Wick 4AL euphonium/trombone large shank mouthpiece from the British instrument maker, with a gold-plated inner rim. Inner rim diameter: 26.00mm Cup depth: DEEP Throat diameter: 7.34mm The mouthpiece offered here appears to be from a very early production run, judging by the engraving. The V-shaped cup provides a slightly darker tone and facilitates easier tonguing. It also allows for good breath support. While it shows some wear and tear due to its age, it is still perfectly usable! Please feel free to ask any questions in the comments.