This worked ok for me, computer built with all the components functioning fine. Only draw back was no instructions, but there are plenty of places on the internet that tell you how to use them.
Here's the basics just for anyone who wants to know.
Wear the strap on your wrist and clip the crocodile clip to an unpainted surface of your computer case then touch the case on an unpainted surface to neutralise the static in your body to that of the case. Keep all your parts in or sitting on their anti static bags until you are ready to assemble and try not to handle them by their circuitry.