ear holes in the core.We have seen great increases in HP and MPG's also where Air Conditioning is a factor we have seen lower vent temps at slow speeds and at an idle,in southern states this is great.We build a lot of these to replace mechanical fans in daily drivers.We use SPAL components.We can be reached at 866-375-9717 or at our website check out our Youtube Video on how we do it. (this a 2 pa