Rock Guard: CSF knows the kind of punishment the front of a car can take on or off the track. The wrong bit of debris flying through the front grille can quickly punch a hole in a cooler. Because the Transmission cooler sits at the very front of the center cooling stack, it is quite vulnerable to damage. The factory grille is the only form of protection for the OEM transmission cooler. However, this still isn't the level of protection many race teams and enthusiasts are comfortable with. To address this concern, CSF has incorporated a rock guard to keep your cooler safe and your X3M/X4M running strong in the event of debris making it through the front grille.