I believe you may be referring to something like I have.
We have 120 degree days here, and the Jeep doesn't overheat with it installed. so no worries there.
It does keep the vast majority of bugs, mud, rocks, birds, cows (well maybe not cows) out of my grille...it was installed by the P.O. of my Jeep. I've found it for sale in quadratec for ~300.00 iirc. so I've kept it. (even though its chrome)