here's more info
"the idea is that they vent gasses that are built up during braking by pad friction. In the "old" days, brake pads used to gas a lot more, and sometimes during hard braking, a layer of gas could form between the pad and rotor and decrease braking distance.
modern day pads don't gas like the old ones, so they are really not needed.
if you just use them on the street, they will probably be okay. But don't expect them to make you stop quicker, they are just supposed to vent brake pad gasses..
If you want to impove your braking, get some aftermarket pads with a higher friction coefficient.
$75 for both is an okay price... although I just get oem rotors for $23 a piece.. ^_^"
it's news to me...