The Extreme design is a cross-drilled only brake rotor. 

Cross-drills are holes machined into a brake disc and are added pathways where debris and heat can escape.   People may raise their concern about drilled holes on a brake rotor and whether this is safe or not, however, these rotors are precisely machined so that the structural integrity of the brake discs is not lost.  This particular design is also meant for everyday, street use and not for the race track or heavy duty applications where the brakes are put under tremendous amounts of stress and could cause drilled only brake rotors to crack.

When comparing this design to another design, such as the Ultimate, the Ultimate design would be recommended for the driver with more aggressive driving habits.  This design will wear less on the brake pads and would pair nicely with our ceramic brake pads.  For consistent stopping performance and a sporty, good look, try the Extreme design brake rotors!