My friend has a cassette that came with his Monty Stock bike. I'ts actually threee little two cog sets that fit together to make a six speed cassette. It's a little hard to explain, but imagine a King Cog that was actually two gears instead of one. Each one is pretty wide so it doesn't dig in easily, and the pairs are matched. It' like a 16/18, a 17/19, and a 20/20 or something like that. It doesn't shift very well, but who shifts these days anyhow. I really like it and would like to pick one up if anyone might be able to point me in the right direction. Has anyone ever seen these things before??