ACDelco Professional Brake Drums are constructed with G3000 SAE qualified material for structural integrity and maximum service life. They are tested to ISO/TS 16949 quality system standards and validated for balance to provide better braking performance. Chamfer angle, vane configuration, and plate thickness all follow the OE design, making them a premium aftermarket replacement for your GM and non-GM vehicle. Also, no machining is required. ACDelco Professional Brake Drums are ready to be installed right out of the box.