Gold plated. 26.10mm cup diameter with a 0.280" throat bore. The Griego 3.5 is great for the tenor trombonist who wants the room of a larger mouthpiece without a huge cup depth. As Griego large bore tenor mouthpieces increase in cup diameter, cup depths are adjusted so as to not become too deep. The combination of wide and deep can cause the player to increase pressure on the rim and tighten the aperture. This can lead to a strained sound in the middle and upper registers. Traditional "New York" style exterior is similar in appearance to Bach models, but slightly heavier, with the weight distributed evenly around the bottom of the cup.