The discs are model specific and are either the same diameter as the originals, as required for many race series or increased to 320mm to increase braking. This means you can use a high performance disc in many race series whilst maintaining the OE calipers if the series rules so dictate. They are 5.5mm thick rather than 4.5mm OE to allow for higher performance and can be used for Road, Track and Full Race use. This gives you World Class Braking at an affordable price.