There is something called natural, is so named because it without special treatment, characteristic of natural cork with the appearance of many small holes, but small holes after being squeezed into bottles away. Treated Cork under the surface fine-pore size, surface hardwood and roughness into Super, Super one, two, three, and so on.
Low Cork cannot be used directly in bottle, because of its uneven surface has many holes, gaps too large can cause wine spills. So the corks to go through further processing, that will fill small holes, filled in. Generated when a process is the first Cork Cork mixed with glue, then scroll and Cork in processor, big hole to fill, and generates no obvious holes, but traces can be seen filling the fill plug.