EBC Premium automotive brake rotors are made from G3000 spec cast iron.

All EBC Premium Discs are cast to a material strength of 150 N/m2 with a tightly controlled surface hardness variation less than 20 HB and are precision CNC machined to a surface tolerance of less than 0.05 mm. That is TWO THOUSANDTHS of an inch. For this reason EBC recommends a maximum runout of fitted rotors of 0.1 mm or .004 inches (4 thousandths) TIR which means total indicator reading on a dial gauge. Runout figures above this will lead to vibration after 3000 to 4000 miles due to what we call disc thickness variation (wearing a thin spot on the high point of the rotor as it runs off-true) which is NOT a warranty condition. So you see this is no cheap import brake disc. These brake discs have the highest integrity and product quality on the aftermarket. An OE quality replacement disc, made of the finest grade iron and a perfect replacement disc for any car. EBC also emphasises that disc must be fitted to absolutely clean hubs free of all dust dirt rust and scale and that COPPER OR MOLY GREASES are NOT used. Such greases contains abrasive particles which can cause runout being similar in effect to dirt particles on your hub.