GDN writes: "The XFPS 4.0 Force is one of those things that you don't really know you need until you use it. The unit plugs into one of the USB units on the PS3 and then either connects to a controller, or to a PC.
When connected to a controller the XFPS 4.0 Force gives turbo functionality to any of the controller's buttons. This is great if you're in an FPS or TPS that has a one-shot pistol or a fighting game where you need rapidly repeated button presses. Not so good for many other games though. But it's not designed for all games."