DENIS WICK Euphonium Mouthpiece ULTRA-X SM Model SM3X Specifications (from product list) Cup Inner Diameter: 26.40mm Rim Width: 6.3mm Throat: 7.45mm Backbore: V-Type Shank: Large Shank Finish: Silver Plated Contents: Mouthpiece, Original Box, Inner Bag, Manufacturer's Product List Purchased new and used dozens of times. It produces a deep and rich sound, but I am selling it because I can't endure long hours of playing due to physical limitations. There is some overall wear and tear. There is a slight dent on the shank. The original box has a tear from the time of purchase. Please understand and purchase accordingly.