7. Here's a look at the ATS converter's piston (left). Notice the dampener in it, just like the factory Ford (right) ones have. We note this because there are some aftermarket pistons that do not (have this damper). The piston also has stiffer springs, and the hub is hardened.
On the other side of the ATS piston, there are tabs that the lockup clutches engage into. The factory piston relies solely upon friction.