These rotors were manufactured with an emphasis on tight tolerances where appropriate, namely the rotor thickness, Other aspects were not as tightly controlled, i.e. errors in the concentricity of machined cross drilled ventilation holes and the cast chamfers were readily apparent to the naked eye. These imperfections however are not indicative of a defective product or design but rather indicate an intent to apply manufacturing costs only where they will benefit the performance of the rotor.