Flugelhorn Mouthpiece Greg Black HYPERSONIC FL GP. I recall that this was a signature model from the mouthpiece importer, B♭ Music. I believe Stork and Black^Hill Greg Black also produced HYPERSONIC models. Unfortunately, the company has already closed down and their website is no longer available, so the details are unknown. The rim size feels slightly larger than a Greg Black 5 rim (0.646 inch, 16.4mm). It doesn't feel as large as a 3 rim, but it feels slightly flatter and has a more pronounced edge than a 5 rim, which is why it feels larger. It is deeper than a standard Greg Black FL cup. It is presumed to be similar to a VFL cup. The blank is more cylindrical than the current FL, and it feels like the weight of a Black^Hill flugelhorn mouthpiece. It has a standard Yamaha shank. I have many other items for sale, so please check them out if you're interested. #TPY's list of items for sale Type...Trumpet