YAMAHA trumpet mouthpiece 19B4NC (Nakagawa model). The size is similar to a Bach 1C, and the cup is slightly shallow. There is a "scoop" on the inside of the rim. The throat is a #28 throat (3.58mm). The backbore is a classical backbore, but it is thicker than the standard YAMAHA model, designed for easier high notes. The 19B4 is an original cup designed by Mr. Nakagawa, not found in standard YAMAHA models. I purchased this at Yamaha Ginza for high-note practice. This is a used item, so please refrain from purchasing if you are sensitive to such things.