Tuba Mouthpiece YAMAHA 69D2 Inner GP Last year, I had the inner GP done at a local music store when I bought it new. The plating cost 20,000 yen. I have the impression that it resonates more than silver plate. It matched any instrument I put it on, so it's a little sad to let it go, but I've found something that suits me better, so I'm selling it. There are scratches from use, but no dents. I think it's perfect for intermediate players. From the YAMAHA website: Rim diameter: 32.86mm Throat diameter: 8.00 mm The inner diameter has a gentle curved funnel shape, and the deep cup is characterized by a symphonic sound. The thin rim and not-too-thick throat make it easy to control even on large tubas, and the weight reduction makes it an efficient and responsive mouthpiece.