Also worth mentioning is the fact that the fins are polished on one side and rough on the other. I assume this is a byproduct of skiving and all the better: the rough side has more bumps so there's more surface area. At the same time it's good to have at least one smooth side to keep too much turbulence from building up. Because the fins are so brittle there's no way they can support a fan; therefore a shroud is used. It's attached on both sides via a pair of small screws and does nothing in directing airflow: its sole purpose is to function as a holder.