ACDelco Professional Brake Drums are constructed with G3000 SAE qualified material for structural integrity and maximum service life. They are d 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 the ideal 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.