YELLOWSPEED ULTRA GRAND REAR ROTOR UPGRADE KIT is a 2-piece design equipped with T6061 billet aluminum alloy centre bell for weight reduced, and it is processed with hard anodizing electrolyte treatment for durability. This kit allows you to increase your O.E.M rotor to larger dimension, and the factory calipers and pads can be retained still. The rotor is made from high level material of alloy cast iron to meet our standard specifications. The rotors with 10mm and 12mm thickness are solid type, while the rotors with 20mm thickness or above are vented type. In addition, this kit can be direct bolt on without any modifications needed to rear calipers and brake pads. This upgraded rotor dimension features better braking performance, attractive look and easy installation. Type A caliper carrier is used for replacing the OE caliper carrier, it’s a lengthened carrier in order to hold the OE caliper and is made of cast iron. Type B caliper carrier works as a bridge between the HUB and OE caliper carrier and is made of medium carbon steel.