This is the Silky Piccolo Trumpet mouthpiece, Symphony Series P5. It has a cornet shank. While the 11AX is well-known for Silky piccolo trumpet mouthpieces, the Symphony Series, compared to the 11AX, seems to offer a fuller and brighter sound. It is particularly recommended for use in large brass ensembles, wind bands, and orchestras where volume is required. The rim size is approximately equivalent to a Bach 5C, the backbore is X, and the throat is 27.