Abstract: A grille having a plurality of s-louvers shaped to increase the efficiency of air flow through the grille without decreasing the effectiveness of the louvers at stopping or deflecting projectiles. Each louver has a hooked portion at the end of the louver to present a ballistic hook for stopping projectiles ricocheting through the circuitous path defined between the louvers. An insert having a closeout for covering the ballistic hook is positioned within each hooked shape portion to eliminate the eddy or stall created at the end of the circuitous path by ballistic hook. The closeout can be penetrated by projectiles ricocheting through the circuitous path such that the ballistic hook can still capture projectiles within the inlet.