It isn't a macro lens, it is actually a lens that is turned around the wrong way. Kind of like binoculars, one way you see far away and the other you see close up.
All up it is a set of 3 extension tubes attached to a 58mm reversing ring with an old pentax lens put on backwards.
Experimentation is the key. Try taking your lens of the camera and holding it against the body backwards, that will give you some idea as to what is happening, but what you will find is the photo's will come out dark. This is because the aperture is closed. You need to use an old lens with manual aperture adjustment allowing you to open it yourself.
It is a bit hard to get the hang of at first but with a bit of patience and perseverance you will come up with some great results like the ones posted in this article.
Thank you all for taking the time to check out my post. If you wish to know anymore about my set up just comment down below.
Happy Snapping :)