A lot of people know about the 2007 espionage involving Ferrari and McLaren. It involved spies, sabotaged fuel, stolen blueprints and the biggest fine in sports history. But off to the side another strange story was happening between McLaren and Renault. Renault got their hands on the designs of a unique suspension component from McLaren. Supposedly, Renault's engineering team couldn't figure out the purpose of the device from the drawing they had "acquired." So what is this device? Broadly, it's known as a mechanical inerter, but in the F1 world everyone still uses the codename originally given to it by McLaren, the J-Damper.