A lot of equipment is needed just to manufacture paper. A whole different set of equipment is needed to make pens. Can you even imagine how much equipment is needed to make a car? We know quite a lot about industrial equipment and supplies, and even we have trouble picturing that one.
The truth of the matter is, though, that industrial plants would not be what they are without the right equipment and supplies. They have to work closely with distributors to make sure they always have what they need. Read a few articles on this website to come to a better understanding.