⚠️This is a 2-piece mouthpiece where the cup and backbore separate, but they are stuck and cannot be removed. Please be aware of this. The following specifications are quoted from the joybrass website. ・Throat: 6.8mm Good breath support, allowing for comfortable playing in all registers for solos, ensembles, brass bands, and orchestras. ・Cup section Rim inner diameter: 25.5mm No. 2 Approximately between 6-1/2AL and 5GS ・Backbore section No. 2 Has a moderate amount of resistance, but allows for good air support (pushing), producing a brighter tone. Suitable for solos, ensembles, and brass bands. If you would like photos from different angles or have any questions, please feel free to comment. I have other items for sale, so please take a look if you'd like.