Thank you for viewing. Bruno Tilz Modell Prof. Daum 3 1/2 B Gold Plated Trombone Large Shank Mouthpiece Detailed specifications are unknown, but the inner rim diameter is larger than 27mm in actual measurement, and the rim is thick. The cup appears shallower than those for bass trombones like Bach. The plating is generally in good condition, but there are scratches on the shank from insertion. There are no dents. There is no case, so the item will be wrapped in bubble wrap for packaging and shipping. Please consider this item as used and understand its condition before purchasing.