Warburton cornet mouthpiece, under part only. It's in very clean condition. It's very convenient because you can play the cornet with a Warburton trumpet top mouthpiece. Regarding the "S" in S10☆, I'm not sure what it means, but the "10" likely refers to a backbore that's slightly wider than the standard 8, resulting in less resistance and a thicker sound. The ☆ mark seems to indicate a more free-blowing feel compared to the normal version. Personally, I think it's a very good specification. It's easier to play than a normal Warburton (personal opinion), so I used to buy the ones with the ☆ mark.