Cast from XG-150 high carbon alloyed iron and undergoing Thermal Stability Profiling. DBA's metallurgy is able to handle the increased stress and heat generated under intense braking application time and time again. Featuring DBA;s patented Kangaroo Paw ventilation that implements a series of 144 diamond and teardrop patterned pillars. DBA achieves up to a 30% increase in surface are and 20% improvement in cooling efficiency compared to traditional straight vane design. DBA's 4000 Series HD variant features a smooth OE style rotor finish Popular for drivers looking for the benefits of a 4000 Series rotor but requiring an OE style look, such as under controlled race division, XG-150 High Carbon Alloyed iron, TSP-Thermal Stability Profiling, THGP - Thermo-graphic paint markings, Direct replacement suitability, Moisture proof corrosion protection packaging