There's some history behind this (and I may not have it completely correct because I'm going from memory ). Graupner in Germany were awarded the license to build small Wankel engines (up to about 100cc IIRC) but didn't have the necessary machinery to make them so asked OS if they would make them. OS didn't have the machinery either but they invested in modern CNC which was the only way to make the epitrochoidal cylinder. The Wankels were sold as Graupner OS (or OS Graupner, whatever ). The big deal about all this was that OS now had CNC machinery which was perfect for mass producing normal 2 stroke engines (which obviously sell in much larger quantities than the Wankel) so they did a total redesign from anything they'd made before and came up with the 40SR pylon engine which soon morphed into the FSR.