[Halon]

I thought the tapered runners were to speed up the air along the walls. The air that's right against the walls gets slowed down due to it hitting the wall, but when the runners taper smaller, that increases the speed of the air, so that all the air molecules move at the same speed. That's what I heard, so it could very well be wrong.

Also, it looks to me that it does have velocity stacks. They aren't as rounded as Magnus's though.