If you wish to earth your laptop and it is one of the new variety of laptops that does not have any metal connections at the back, you will need one of these in addition to an earthing lead. It is a Belkin USB extension cable. This particular USB cable is fully screened - many USB cables are only partially screened along the length. This screening is necessary in order to be able to earth the laptop! The nice thing about using this for your earthing purposes is that it can also be used as a normal USB extension cable.