To extend the range of the USB adapter, for example if the USB adapter is plugged into the back of your PC it might not be practical without the extension cable as its out of sight.
Sorry for my lack of knowledge, but what is the USB cable for in the box?
Great price. Ordered yesterday. Arriving today. Finally replacing my 360 controller. Forgot to add heat when I saw this yesterday and can't do so now as it's expired. (fierce)
I'll the kids to give run on rocket league for them to test (y)