At 8:25 in the WCW video, he talks about the holes being rough on the media side. But if you look at the center tube, it has a spiral wrap with a raised ridge on the media side, which keeps the ends of the media pleats from touching the holes in the center tube. So even if the hole punching is a little rough on the media side, it doesn't matter because the media can't touch the holes due to the raised spiral.