They are cheap copies of the proper item and generally don't work very well, the software is free to download and use as the 'serial number' is housed within the adapter/lead which the software reads when connected, I don't think you will get all functions from the copy units.
Never personally used one but not heard anything good about them but the amount you see for sale makes me wonder, if they didn't work people wouldn't buy them and there wouldn't be so many around !